The only software strictly needed for following along the recipes of this book is the official 2.66a Blender release, although the just released 2.67 and 2.67a Versions work perfectly fine (but if you use the latter ones, be aware that something in the graphic look of the nodes has changed, especially for node groups. In any case, the working principles are the same). You only need to download it from www.blender.org/download/get-blender. Any particular texture needed for the exercises in the book is provided as a free download on the Packt Publishing website itself.

Not essential but also handy can be an image editor, in case you want to adapt your own textures to replace the provided ones. I suggest The Gimp, an open source image editor that you can download from www.gimp.org. Any other software you prefer is perfect anyway.