According to a discussion at
http://groups.google.com/group/micro...fc616d7d4047f1
You can delete the Program Files, Windows, and Documents and Settings folder. Then delete the following root files.
a.. Boot.ini
b.. Ntbootdd.sys
c.. Ntdetect.com
d.. NTLDR
e.. Hiberfil.sys
f.. Pagefile.sys
You will need to do this by booting from the XP CD and load Recovery Console.
You can then reboot with the XP CD and choose the location for setup. Do not format.
In any procedure as intensive as a OS change, make sure you backup all important data.
Arun