You can take three basic approaches to ensure hardware compatibility. The first is relatively simple and may prevent your having to purchase anything new. Microsoft has done most of the compatibility testing for you already and posted that information in its Hardware Catalog (see Figure 2.1). (They used to have an online Hardware Compatibility List [HCL] for XP, but no longer.) Now you look at the Windows XP Catalog online, at

http://www.microsoft.com/windows/catalog

Figure 2.1. Use the online Microsoft XP Catalog to check on your hardware before you either purchase or decide to upgrade to Windows XP.

Then click on Shopping for a new PC? At least that was the link as of this writing. Otherwise, poke around until you find links for various types of hardware. Typically it will be a navigation bar on the left side of the Web page, with drop-down lists for classes of hardware. If the “Designed for Windows XP” logo is listed next to the product, then you know it will work. Some products have a clickable link under them. Clicking on such a product's link opens another page that may offer additional compatibility information.

If your hardware isn't listed, that doesn't mean setup on your PC won't be successful, but there is a chance you'll encounter problems. XP has been around long enough that many XP drivers are now available that aren't necessarily Microsoft-certified.

Don't know what's in your system or not sure if you thought of everything that might conflict with Windows XP Professional? No problem. You can run the Windows XP Compatibility Tool (testing program) from the CD. This program detects your hardware and verifies compatibility. Insert the CD (you'll have to borrow one from someone who has it, if you don't want to purchase it just to find out), and choose Perform Additional Tasks from the main menu. Then choose Check System Compatibility. During a system upgrade, you will see the option for this on the introductory screen. (You can also run the tool from the command line by typing <CDROM DRIVE>:i386winnt32 /checkupgradeonly. You can perform just the check and then exit the tool without installing the operating system, if you wish.)

When you run the program, a report is generated telling you whether your computer cuts the mustard.

What do you do if some component of your system (or your entire computer) doesn't rank high enough to appear and isn't listed in the compatibility list? Well, you can wing it and see how things work out. Just install XP onto the computer in a separate directory or disk partition (dual-boot); then see what happens. If this approach doesn't work, you can revert to using your old operating system, having only lost an hour's time. You should also approach the hardware manufacturer and ask whether a Windows XP driver is available for the component. (How to set up a dual-booting arrangement is discussed in Chapter 3.)

It isn't a bad idea to just bite the bullet and shell out for a new machine once every two years or so. I'm a holdout myself, even though I'm a techno-junkie who often has to be an early adopter of new hardware. The bottom line is that I'm cheap, so I try to squeeze out every last CPU cycle from my computers and keep them running for a very long time. I'm still using an old machine based on Intel's 386 processor (which is two generations removed from the original Pentium) running DOS as a router to the Internet. Clearly, I don't like to participate in the “throw-away society's” idea of planned obsolescence. But every time I upgrade to a new computer, I notice a significant number of niceties across the board, for example, quicker response; more inclusive power management so my system uses less power when it's idle (and cuts my utility bills!); reduced energy consumption due to lower chip count (which also cuts my utility bills!); more hardware setting options; a faster DVD drive with support for CD-ROM media; high-speed ports such as USB and FireWire (also known as i.Link and IEEE 1394b) that work with the newest scanners, printers, and drives; faster video display; and so on.

If you have decided to start fresh and purchase new PCs for your personal or corporate arsenal, let me suggest an easier way to choose them than to research each piece separately. On the Windows Catalog site, just click on the Hardware tab, and then Personal Computers and choose a system style (desktop, laptop, and so on) and find one in the list. Microsoft's testing lab awards the “Windows XP-Ready PC” merit badge to computers that meet their requirements.

There's no shortage of systems there, so get ready to do a little head scratching.

Don't want to purchase a whole new computer, but your hardware isn't all on the Catalog or the HCL? Or do you have some old, stodgy disk drive, SCSI controller, video adapter, motherboard, or some other piece of gear that you want to upgrade anyway? You're not alone. The PC upgrade business is booming, as evidenced by the pages and pages of ads in the backs of computer rags and the popularity of computer “swap meets,” where precious little swapping is going on except that of hardware components for the hard-earned green stuff. If only my co-author and I had written Scott Mueller's book, Upgrading and Repairing PCs, we would be very happy authors. It's perennially one of the best-selling computer books.

The next few sections describe upgrading your PC for operation under Windows XP Professional in case you're the incurable upgrader type and want to take that route.

So, you want a general upgrade to the performance of your system? The cheapest upgrade you can make is probably to add more RAM (see below). But if your wallet allows, and you want to get to the core of your system for a serious upgrade, start with the motherboard. Don't bother upgrading just your CPU without upgrading the motherboard too. While CPU upgrade kits are available to allow some older systems to use newer processors, recent changes in CPU speeds, physical packaging, and electrical requirements mean you're much better off upgrading both the motherboard and the CPU if you need a speed boost. Even if you're considering a RAM upgrade, do the motherboard/CPU upgrade first because a new motherboard often uses a better, faster type of RAM than your current system does. Motherboard improvements roll down the pike every few months, and adding a new CPU to an old design isn't going to net you much.

Motherboards are pretty cheap—typically around $100–$150 even for a good one, such as an Intel, Supermicro, Abit, or ASUS (this price is sans CPU); figure anywhere from $75 to $200 bucks more for the CPU, depending upon how close to the “bleeding edge” you want to go). Don't get a motherboard from a company that doesn't put its name on the board, doesn't have a good Web site for technical support, or doesn't have a phone number. It's not worth saving a few bucks. Also, check the Microsoft Catalog, of course, to see whether it's been tested. (Look under “Other Hardware” on the catalog page.) Get a board with the latest system memory and a chipset that was designed to make it work optimally with the CPU you selected. (See the next section to learn about the importance of chipsets.)

Obviously, you'll want a modern motherboard with a snappy CPU. So, get your hands on a motherboard that supports the ACPI power management scheme (not just APM) and a reasonably quick processor (in the 1GHz to 3GHz range), such as an Intel Pentium 4 or AMD Athlon 64 (or the older Athlon XP). If performance is your game, check out the hyper-threading Intel Pentiums. (This technology makes it possible for a single CPU to process information similar to how a dual processor system does.) It should have a fast internal bus (called the “front-side bus” or FSB), support for ATA-100 hard drives (or better, serial ATA drives) and AGP or PCI express graphics, a flashable (upgradable) BIOS for later upgrading, and it should be designed around the processor you have in mind. In fact, it should come with the CPU installed. Installing a CPU isn't that difficult, but if you don't do it right, the CPU can overheat and croak.

This goes without saying for anyone who has built a PC recently, but virtually all new motherboards are of the “ATX” format (though a few newer form factors are available, notably microBTX). These motherboards don't fit in the older AT-style cases and don't work with the AT power supplies either. ATX power supplies work hand-in-hand with the ACPI chipset and operating system, allowing the software to control the power states of the PC, including sleep, suspend, soft power down and up, and so on. There are some AT-style boards available still, but I suggest getting a new case and power supply and opting for the ATX version of whatever motherboard you're considering. A new case and power supply shouldn't cost you more than about $60 (though better cases/power supply combos can cost upwards of $100).

When you install Windows XP on an ACPI-based system, you might need to update the ACPI BIOS to get the full benefits of Plug and Play and power management. If you don't do the update, you might have any of the following problems:

To obtain an update that should prevent these problems, contact your computer's manufacturer. Actually it's a good idea to contact the manufacturer (or check their Web site) even before you install XP. If you can get the latest BIOS update, the XP installation will go more smoothly and the ACPI features such as power management are more likely to work properly once XP is installed. BIOS upgrades are available for many laptops as well as for desktop computers.

If you really want to delve into the research, check the Usenet newsgroups. Point your newsreader to

alt.comp.periphs.mainboard

If you're going to be running applications that can actually benefit from multiple processors (check with the software vendor because not all applications do), then you should consider going full bore with a dual-processor motherboard. Although Intel's processors were the only players in this game until mid-2001, AMD's Athlon MP now provides you with a cost-effective choice.

Suffice it to say that older systems based on 386, 486, and early Pentium processors are now out of the picture. If you want to keep these machines in service, put less-demanding versions of Windows on them, and network them as clients into your Windows XP or 2000 LAN.

Keep in mind that the CPU is only a very small part of the overall design of a motherboard and computer. Many people ask me about upgrading their computers by simply dropping in a (relatively) expensive CPU chip or going through all kinds of machinations to speed-double the chip, and so forth. Just like you don't become (Governor!) Arnold Schwarzenegger or Rambo by getting a brain transplant (you need the body, too), you can't create a supercomputer just by upgrading the CPU. Efficiency of the CPU is interdependent with several variables, such as the support chipset and the internal system bus speed. In fact, contrary to popular belief, the efficiency of the computer is more affected by the chipset than by any other factor—not the CPU nor the video nor the hard disk.

The CPU can be changed. The memory can be upgraded. The hard disk can be swapped. But the motherboard has been designed around the capabilities of the chipset, and until you change the motherboard, your PC will function largely the same. You cannot upgrade the chipset on a motherboard; you have to replace the board. Desirable chipsets support the following features:

You can see that the chipset is at the very heart of much of what the computer does. Because it cannot be upgraded, though, there isn't much talk about it, and people tend to forget about its centrality. Equally important to the overall design of the chipset is how well the CPU and chipset engineers communicated during the design of the chipset. Doing your homework on the latest chipsets and their compatibility/performance with specific CPUs will serve you well.

When you're scoping out a motherboard, think about how many slots you will need for plug-in boards (which can include cards for your sound, video, modem, and so on). More and more hardware is built onto the main boards now because very large-scale integration chips (VLSI) make it possible; therefore, you'll tend to need fewer slots than in the past. Often network support, audio, and even AGP video are built into the motherboard. If you want to use your own sound card and special super-duper video adapter, you can save a few bucks by getting the “bare-bones” version of a motherboard that does not include sound or video on it. However, if you want to avoid the hassle and keep more slots available for your other boards, buy the motherboard with this stuff integrated on it (such as on-board audio, which provides lower-cost—and lower-performance—audio capability that should suit your needs, unless you need high-end workstation performance, performing video capture or editing sound files). For one thing, all the parts are guaranteed to work together. If you think you'll want to add your own boards for the motherboard-included functions, make sure you can turn them off (usually with jumpers or software settings in the BIOS).

As of this writing, most motherboards were strong in PCI slots and have phased out ISA slots. Few have even one ISA slot these days. And most motherboards now have either an AGP (Accelerated Graphics Port) slot or a PCI Express slot for plugging in a fast video card. AGP is based on the PCI bus but fine-tuned for the needs of high-performance 3D graphics.

Like other versions of Windows NT, Windows XP Pro uses the memory it finds in the system intelligently. And it loves memory! The cheapest and easiest upgrade you can make to your PC is to add RAM. If your computer seems to “hit the hard disk” (that is, you have a delay in activity and you hear some clickity-click sounds in the computer and see the disk access light on the front of your system flash annoyingly) every time you click something or move the mouse around, Windows is doing way too much disk swapping (accessing data from your hard drive rather than system memory). You should be able to quickly switch among 5 to 10 programs without a lot of wait or noise from your PC. Go get some new memory that matches the kind of board you have (read the motherboard or your PC's manual), and carefully install the memory. Unplug the computer. Open the case, and find the RAM slots. Touch the metal case with your other hand before inserting the RAM. (RAM chips are very susceptible to damage by static electricity.) Get the fastest kind of memory that your motherboard can take advantage of.

Modern motherboards automatically detect memory you install (no switch setting is necessary), and Windows XP reads this setting and uses it as necessary. In general, the more memory you have installed, the better. As mentioned earlier, Microsoft suggests 128MB for decent system performance. If you're running lots and lots of programs at once, I suggest more on the order of 256MB to 1GB. For the record, I've found 128MB adequate for even running 10 or more programs, while many folder windows were open, along with a couple of browser windows.

I'm writing this chapter on a PIII 1GHz laptop with 128MB, and it's plenty zippy. I typically have more than 10 programs and/or windows open, playing MP3 files, checking email in the background, and browsing the Web. Another machine of mine has 1.5GB RAM and does a whole lot less disk swapping. At this point, generic mid-performance memory is so inexpensive that there is no reason not to upgrade if you need to. The high-end stuff (fastest RAM) will cost you a bit more, however.

You need approximately 1.5GB of free hard disk space just to install Windows XP. This amount is just a little indication of Windows XP's storage hunger. With bloatware on the rise (programmers figure why bother making programs fast and tight with storage being so cheap, I guess), it behooves you to have lots of storage space. Like upgrading RAM, upgrading the hard disk is easy these days—even on the pocket book. Get down to Costco, or check www.buy.com for the latest prices on hard disks. They continue to plummet. For less than a hundred dollars, you can get a huge disk. I hesitate to even quote sizes. It seems that every year sees an increase of a factor of ten in storage capacity. In any case, the 1.5GB you need for the installation will look like nothing.

As with RAM, modern motherboards autodetect and configure hard disks when you insert them. Installing the current crop of ATA drives has become very easy. The biggest nuisances with drive upgrades are figuring out whether to ditch the old one or keep it, deciding which drive will be the boot drive, and figuring out how to back up and restore. The EIDE spec allows for four drives, one of which is probably your CD-ROM. That typically leaves room for three, unless you have a CD-RW or another type of removable-media drive (such as a Zip or SuperDisk drive) in the box. There are too many options to cover here, but the easiest upgrade path is to make the new drive a “slave” on the primary IDE channel. Make sure to set jumpers on the drives' circuit as necessary, and ensure that you have the necessary cables to hook up the drives. Jumper your boot drive as master and the secondary drive as slave.

A newer type of ATA drive, called Serial ATA, uses smaller, simpler-to-connect cables and transfers data much faster than ATA or UltraATA drives. The cables on normal (parallel) ATA drives are bulky, inflexible, fragile, and too short. This caused hard disks and optical drives to be placed in strange positions and resulted in many frustrated system builders. The width of those cables also blocked airflow within the computer's box, and with modern CPUs and video cards generating so much heat, good airflow is essential to a stable system. Serial ATA (S-ATA as opposed to P-ATA) drives also can transfer data at a slightly faster rate than typical P-ATA drives. First generation S-ATA drives run at a bandwidth of 150MB/second. This is a seemingly disappointing 13% improvement over the popular P-ATA standard called Ultra/ATA 133 (133MB/second). However, today's hard drives rarely ever use that much bandwidth, so 150MB/s is more than enough. In later incarnations, S-ATA will run even faster.

If you want to install another hard disk (instead of removing the one you already have) and both of your IDE cables already have two drives connected, you can add additional ATA/IDE ports with an Ultra ATA/100 adapter card from Maxtor (www.maxtor.com), SIIG (www.siig.com), or Promise Technologies (www.promise.com). All you need is an empty PCI slot to add support for up to four more IDE/ATA drives.

Unlike NT, Windows XP can be installed on large removable media. The Setup program doesn't look to determine whether the target volume is removable. The %SystemRoot% (WINNT) folder is typically on a fixed hard disk, but it could be on a removable disk. One advantage of this option would be to install, say, Linux on one removable drive, Windows NT 4 on another, Windows 98 on a third, and so on.

Because a doggy, older video card can bring even a snappy system to a crawl when you scroll the screen or move a window around, you'll want to find yourself a fast AGP card if your motherboard has an AGP slot. Microsoft has made the move to support video quite nicely in Windows XP Professional. You have the option of connecting up to ten monitors, for example, and using them together. You should check your video cards' specs and the Windows Catalog site to see whether they will work in multimonitor arrangements before purchasing, though.

Generally speaking, most popular Super VGA–compatible video cards will work with Windows XP, but if you're thinking about upgrading for more speed or features, research what's up with the latest AGP boards that have the bells and whistles you want—TV out, video capture, a fast 3D chipset for games, whatever; any recent motherboard which doesn't have on-board video will have an AGP (Accelerated Graphics Port) slot. Decide the resolution you want to use, and make sure the card supports the number of colors you'll need at that resolution; if you choose a video card with at least 16MB of RAM, you can handle resolutions up to 1,600x1,280 with 24-bit (16.8 million) color. If you have a 17-inch CRT or 15-inch LCD monitor, you'll want to be running at 1024x768 resolution. Make sure the board can run at 72Hz refresh rate at the color depth and resolution you desire, too, so you won't see flicker on your CRT screen (LCD monitors don't require a high refresh rate). P.S. Your monitor needs to be able to do it, too. Check the monitor specs. Some older monitors can't run at, say, 1024x768 while refreshing at 72Hz.

The speed of AGP boards (and connectors on the motherboard) is ever increasing. As of this writing, the fastest AGP hardware ran at “AGP 8X” speed, which means eight times faster than the speed of original AGP boards introduced in 1996. Keep in mind that your motherboard and video card have to support the same speed (4X,8X, etc.) to gain the benefits of a fast card. PCI Express is an emerging standard that promises to replace both standard PCI slots and the AGP slot over the next few years.

If you're looking for a new monitor for use with Windows XP, keep in mind that 15-inch LCD panels have about the same usable screen space as 17-inch conventional monitors (CRT), a 17-inch LCD is equivalent to a 19-inch CRT, and so on.

Windows XP comes with a large complement of 32-bit driver support for many devices, including a wide variety of video cards. It's quite likely that your card is going to be recognized, but you should check with the online Windows Catalog just to make sure, as mentioned earlier in this chapter.

Plug and Play (or PnP, as it is commonly abbreviated) has brought a new level of sophistication to the PC. Much of the headache of PC upgrades stemmed from internal conflicts between plug-in boards and peripheral devices that were not easily detected by the operating system and too difficult for users to configure. Installing even a simple modem was often an exercise in failure for many users as they struggled to determine and set the board's jumpers, dip switches, or software settings to use an available IRQ (Interrupt Request). With PnP, you just plug in a board, screen, printer, scanner, or other peripheral, and reboot.

PnP doesn't always work as advertised, but most of the time it does, and it's a big step in the right direction. NT-based platforms began supporting PnP with Windows 2000. Now with XP, PnP installations are easier than ever. If XP can't find a driver when you install a device, the Windows Update site will be queried. There are currently thousands of drivers on the Windows update site. Chances are good the system will automatically find a driver for you somewhere.

You are probably aware of a distinction to be made between types of programs. Most programs folks use on a daily basis are called productivity applications or simply applications. They include programs such as Microsoft Word, Microsoft Access, Adobe Photoshop, Dreamweaver, and other Web page editors, CAD-CAM programs, video and sound editing programs—just to name a few of the thousands that are available. Typically, such programs help you produce documents in a certain line of work. These applications run at the highest level of the computer system, well on top of the operating system, and don't get down into the nitty-gritty of it.

By contrast, utilities are programs that try to get down deeper into the operating system and are used to manage the computer. Programs such as virus eradicators, hard disk partitioning and image backup tools, hard disk organizers, user interface tweakers, and power management tools fall into this class of programs. Norton System Works, Ontrack Partition Magic, and McAfee Anti-virus are examples.

Even though most people don't typically distinguish between utilities and applications and simply use the word application (or just program) to refer to any program, technically, they are different. As you'll see, it's very likely that your existing applications are going to work under Windows XP Professional. However, it's far less likely that the system or disk utilities you want to bring over from less-empowered iterations of Windows will work without being updated.

As you might recall from Chapter 1's brief discussion of the XP architecture, when applications need help from the operating system to, say, print or write a file to disk or accept keyboard input, the environment subsystem passes the request to the Executive. The NT Executive runs in protected mode so that applications (or utilities) can't threaten the stability of the system. The requests that applications make are known as API calls. (API stands for application programming interface.) APIs are built into each environment subsystem and make up a set of tricks or canned functions the programmer can call upon.

The NT Executive, kernel, and hardware abstraction layer (HAL) take care of the rest of the work after the request is made. Recall also that the non-Win32 environment subsystems turn their calls over to the Win32 subsystem, which then routes them to the Executive. Thus, the environment subsystems have to translate native Windows 3.x, OS/2, and DOS calls into Win32 calls, which are then passed to the Executive using API calls the Executive understands. A lot of interpreting goes on, and lots of middle management.

For general applications, all this is just peachy because most applications just want traditional access to hardware: keyboard input, screen output, printing, and reading and writing data files on disk. APIs are a great help here, as is the Executive, because applications programmers don't have to handle the drudgery of system housekeeping on their own. The existence of an API makes writing Windows programs much easier.

As you might have suspected, any program or utility that wants to work directly with hardware, or makes calls that would otherwise be trapped because they don't exist in the Windows XP environment subsystems, will fail or will likely be crippled in some way. Typically, Windows XP shuts them down after generating an error message of some sort, possibly asking if you want to try a solution on the Windows Update Web site. Exceptions are legitimate calls to COM and LPT (serial and parallel) ports made by DOS programs in the course of traditional procedures such as dialing a modem or printing a document. Many DOS communications programs expect to access the serial port UART (the chip that runs the serial port) directly, for example. NT “virtualizes” the PC serial and parallel ports in the 16-bit subsystem, intercepting the request and sending it through the Executive as legitimate. The port is emulated in software, basically, and the DOS program is none the wiser. DOS programs that try anything more sophisticated, such as writing to the hard disk tracks or doing fancy stuff with the ports, screen, or keyboard, will be trapped.

In Windows 3.x, API end runs often were neither perceived nor prevented, resulting in system breaches and crashes. This was particularly a problem with DOS programs because they assumed they had control of the entire computer (DOS isn't a multitasking operating system). Windows 3.x allowed this use, so games and utilities programmers took advantage of this “feature” to write some pretty audacious programs. DOS-based viruses are a good case in point. Viruses make a hobby of fiddling with the innards of your operating system (typically by altering data on the hard disk), with insidious effects. Windows 3.x couldn't prevent such security breaches because it had no way of knowing they were occurring. Windows XP (and 2000) are much better at preventing them. The BIOSs of modern PCs can also detect attempts to futz with the boot tracks of the hard disk, too, though the feature can be defeated through disabling the antivirus or write-protect boot sector setting in the BIOS Setup utility.

Windows 9x and Windows Me were somewhat better at protection than 3.x, though not by a great margin. Portions of the kernel were protected, and if a program acted improperly, you stood a better chance of being able to kill it without bringing down the whole operating system. The designers of Windows 9x and Me achieved a higher degree of hardware isolation by virtualizing all the hardware, the same approach used in NT, 2000, and XP. Every physical piece of hardware in the computer is accessed only by virtual device drivers (called VxDs in Windows lingo). When an application wants to use device, it asks the operating system for it via the API call. Then the operating system validates the request and passes it along to the device driver, which in turn handles the actual communication with the device.

As with previous Windows versions, Windows XP allows the user to define certain characteristics for running DOS programs, through PIFs (Program Information Files). PIFs allow you to set default properties for MS-DOS programs, such as font size, screen colors, and memory allocation.

Intel and compatible CPUs have capabilities that come to the rescue, to some degree, in helping prevent hardware access breaches, yet still handle the request. The CPU works in concert with the operating system to achieve the desired result. When a DOS program running in Windows tries to access hardware, Windows maps the DOS API call to the Win32 API. This procedure is fine until a direct call to hardware is attempted. An intelligent feature built in to Intel 386 and subsequent chips (up to and including the Pentium 4 as well as compatible processors such as the AMD K6 family, Athlon and Duron), called the I/O permission bitmap, comes to the rescue by noticing this request and putting up a red flag.

When an application is run, Windows XP detects what type of program it is—whether DOS, Windows 3.x, 32-bit Windows, or OS/2. When the VDM (virtual DOS machine) for a DOS program is set up, it provides all the basic services of a PC, and it also creates an I/O permission bitmap for the application. The bitmap is essentially a table with entries for each of the computer's internal ports (there are many, used for different things, such as the system clock, network boards, and so on), and it shows which, if any, of the ports allow direct access. If the DOS program tries to access hardware outside this accepted list of virtualized hardware, the red flag goes up, Windows XP notices it, and the program is terminated, typically accompanied by an entry in the system error logs.

Enough theory. What does this mean to you and to your application choices? Most of your older software will probably run fine after the upgrade. But if you're upgrading from Windows 3.x or 9x and you've been running older 16-bit programs, especially hard disk utilities, you might have some trouble.

As mentioned, Setup examines the applications you have installed and attempts to warn you of incompatibilities. In some cases, you'll just be told to bag the program. In other cases, you'll be prompted to contact the maker for updates, called upgrade packs, or to insert the disks with upgrade packs on them at the appropriate time.

So, which programs are really ready for Windows XP? The logo requirements for “Windows XP-Ready Software” are similar to those discussed previously for hardware. Just check the product's packaging or the Web page description of the product you're thinking of purchasing. If it's Windows 2000-compatible, chances are good that it will run under Windows XP, but that's not guaranteed. I suggest you contact the maker or check a few sites on the Web first.

I've added RAM to my computer, and it doesn't seem to show up.

You must check several things when adding RAM to ensure that it shows up correctly in Windows. If the BIOS detects the RAM, you can be assured that it will be detected in Windows, so don't worry about any settings within Windows per se. Just do what is necessary for the computer to report the correct amount of total RAM when it is booting within the BIOS. Older machines used to require switch settings or BIOS setting adjustments when you added RAM, but virtually all new computers do not. Of course, you can and should always consult the manual supplied with your computer when performing a RAM upgrade. Follow this checklist:

Where can I learn more about compatibility and upgrade options for my Windows XP computer?

Microsoft maintains several resources for Windows XP. You can check the following: