Answer
Got your xp cd? then put that in the drive and restart! follow on screen directions!
http://www.theeldergeek.com/clean_installation_of_windows_xp.htm
http://www.theeldergeek.com/clean_installation_of_windows_xp.htm
http://www.michaelstevenstech.com/cleanxpinstall.html
take your pick from those links
hope that helps!
:-)