How to Downgrade Vista to XP Without Reformatting
Of the two approaches to downgrading Windows, the first is more convenient, as it doesn't require you to wipe your hard drive. You will need a genuine Windows XP installation CD; if all you have is a recovery disc, use the "Start from Scratch" process that follows.
Before you proceed, make sure you have several gigabytes of free space on your boot drive (usually C:). Take a moment to back up your entire hard drive; if you have Vista Business or Ultimate, you can do so with the Complete PC Backup and Restore tool, making it easy to get back into Windows should this process hit a snag.
Start by booting to your XP disc: Just insert the disc into your drive and turn on your PC, then press the spacebar when it says Press any key to boot from CD... If you don't see this message, you'll have to enter your PC's BIOS setup screen and change the boot options so that your CD drive appears above your hard drive in the boot sequence list. Consult your PC's manual for details. (If you can't boot from your CD, you can download free XP Setup boot disk files by searching for Q310994 at support.microsoft.com.)
When XP Setup starts, press R on the first page to open the Recovery Console. If you are asked to choose a Windows installation, type a number (usually 1) and press Enter.
In some cases, you may be asked for the Administrator password at this point. If you don't know it, you'll have to boot back into Windows Vista, open the Start menu, type lusrmgr.msc, and press Enter. Open the C:\Users folder, double-click on the Administrator account, and turn off the Account is disabled option. Open the Start menu again, type Control userpasswords2 into the Search box, and press Enter. Next, click the Reset Password button, choose a new password, and start over.
Use XP's Recovery Console to replace the Vista Boot Manager with the older version compatible with XP Setup.
Now. at the Recovery Console command prompt, type the following commands to prep your hard disk for XP:
fixboot
fixmbr
cd \
ren windows winvista
exit
fixmbr
cd \
ren windows winvista
exit
When your PC restarts, boot onto your XP CD once again, and then proceed with setup normally.
When setup is finished, you'll have to move everything manually. This includes your documents, the contents of your desktop, and any other personal data that you'll need from Vista's now-defunct C:\Users folder into XP's C:\Documents and Settings folder. You'll also need to reinstall all your applications and device drivers, and eventually delete the abandoned C:\Winvista folder.
