Boot from your Windows XP CD and tell the setup you want to format your harddrive before it installs XP.
Make the right choices on http://www.windowsreinstall.com for a detailed instruction.
Just to check: are you sure you've got all necessary drivers, the setup-files of all your application programs and a copy of all data you don't want to lose?
Hope this helps.
I want to format my main hard drive. I do not have a floppy drive to make a bootable disk. I tried using the Maxtor software that came with the drive when I first bought it. It will not let me format the drive because it is my boot drive. How do I get around this? I have Win XP. Please Help.