Oh man, that is not an easy or quick task, by any means. I had to do the exact same thing when I upgraded from Windows ME because if you install XP over ME you will have problems. Then I had to do the same thing all over again when I installed a second hard drive. The most difficult part will be storing everything you want to save on something other than your hard disk. As far as the reformatting process, the Microsoft support website has excellent documents explaining exactly how it's done, and I also went to the website of my hard drive manufacturer and got some more great information. You might possibly have a problem if you are using the "upgrade" version of XP and it doesn't detect a previous installation of Windows because you've cleaned off the hard drive. It won't accept an OEM disk (the one that comes with preinstalled operating systems), so I had to buy a Windows 98 disk and put it in the CD-ROM drive during the XP installation, so it thinks I had an earlier version of Windows. (If your previous operating system was store-bought, you won't have this
problem.)

Good luck, have fun !