Make sure you copy all of you personal documents as pictures, music, etc…
get the windows xp cd, pop it in and re-start the computer.
(if the computer do not start from the cd you will need to go to the bios and change the boot, making the CDrom your fist boot order then the Hard drive)
after the computer is restarted in the CD it will ask you all the option from the windows xp installation.
It is that easy… you don’t need any other program.