On occasion there will be times when a repair install can't be performed while still being able to save your files and folders. The XP installer at that time will simply delete the current installation(Windows, DocumentsandSettings, and Program Files) without clearing all data off of the existing partition. This would be seen with the same XP install disk used for the original installation. If another disk such as going from one with SP1 to a cd with SP2 the newer release will need to reformat the existing partition for the fresh install there.