How to Uninstall Windows XP: If upgraded your computer to Windows XP from a previous version of Windows, Windows Setup Wizard may have backed up your current operating system. (The windows backup files are named Backup.cab and Boot.cab and have been stored in C:\Undo directory, that's assuming that Windows is installed on your C:\ drive.) If it is, you may uninstall Windows XP and return your old Windows OS (operating system). Be sure to backup all of your data files before you start to uninstall Windows XP. Or you will be sorry.
Note: If you have made any changed your partitions or drives since installing Windows XP, you usually can't uninstall it.
Follow these steps to uninstall Windows XP!
1. Go to >Choose Start >Control Panel >Add or Remove Programs.
2. Look for Windows XP Uninstall, if Windows XP Uninstall appears in the Currently Installed Programs, then you can uninstall it.
3. Now click on Windows XP Uninstall. Additional information should appears.
4. Now click on the Change/Remove button. You should see the Uninstall Windows XP dialog box.
5. Now choose Uninstall Windows XP and click on Continue.
You need to follow all of the directions on your screen. After the uninstall process is finished, your computer restarts and runs your previous Windows OS (operating system).
Note: Uninstalling Windows Xp doesn't delete your all your data files. However, most programs that you have installed after you installed Windows XP probably won't work. All you have to do to fix this, just reinstall them again. If you have created any documents or files, they should still be stored in C:\Documents and Settings\username\.