If you upgraded from Windows 98 or Windows ME, and chose to save uninstall
information, you can remove Windows XP by going into the Control Panel /
Add/Remove Programs / and choosing to Uninstall Windows XP from the list of
software.
If you upgraded from Windows 2000, or didn't choose to save your uninstall
information, you'll have to reformat your hard drive, and install another
operating system.
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Mike Kolitz MCSE 2000
MS-MVP - Windows Setup and Deployment