How To Repair A Windows XP Installation
Insert the Windows XP CD into your computer's CD-ROM, and then restart your computer you should get the mesage press any key to boot from cd, do so
windows should now start to load you will be asked to press F6 if you want to install third party SCSI or RAID drivers, unless you are runng raid then don't bother just let it continue.
When completed loading files, you will be presented with the "Windows Setup" screen, and your first option. Select "To set up Windows XP now, press ENTER". DO NOT select Recovery Console.
You will be presented with the windows licence agreement just press F8.
Windows Setup will find existing Windows XP installations. You will be asked to repair an existing XP installation, or install a fresh copy of Windows XP. Select repair
If no installations are found, then you will not be given the option to repair. This may happen if the data or partition on your drive is too corrupted.
Windows XP will appear to be installing itself for the first time, but it will retain all of your data and settings. Just follow the prompts, and have your CD-KEY ready if needed.
Thanks to Den1 for this guide