In general, Apple likes to keep things simple. Everything it ever says about the iPhone suggests that you can sync only one iPhone with one computer.

That's not really true, however. You can actually sync the same iPhone with multiple Macs or PCs.

And why would you want to do that? So that you can fill it up with material from different places: music and video from a Mac at home; contacts, calendar, and iPhone applications from your Windows PC at work; and maybe even the photos from your laptop.

iTunes derives these goodies from different sources to begin with—pictures from your photo program, addresses and appointments from your contacts and calendar programs, music and video from iTunes. So all you have to do is set up the tabs of each computer's copy of iTunes to sync only certain kinds of material.

On the Mac, for example, you'd turn on only the Sync checkboxes for the Music, Podcasts, and Video tabs. Sync away.

Next, take the iPhone to the office; on your PC, turn on the Sync checkboxes only on the Info and Applications tabs. Sync away once more.

Then on the laptop, turn off Sync on all tabs except Photos.

And off you go. Each time you connect the iPhone to one of the computers, it syncs that data set according to the preferences set in that copy of iTunes.