The first thing the XP installer will do is delete the default Windows, Program Files, and Mydocuments right from the start. But XP will readily install to the current Fat32 partition without a need to wipe the drive. This will save files and other things in other folders. But for the best overall performance when going from a dos shelled OS to one with an NT core XP will run best on it's native NTFS type partition. You should plan on backing up things anyways whenever you decide to change versions of Windows as well as different OSs to prevent losing anything important.