Here's a bunch of reading for you or your mate
uninstall xp to 98
uninstall xp reinstall 98
This is the jist of it unless you have other circumstances:
The normal way to "uninstall" _any_ operating system is to format
the hard drive and install a new OS of your choice.
However, if you performed an upgrade from Win98/Me, elected to
backup the old system files, and didn't convert the partition to NTFS,
then all you need do is boot into Safe Mode and Start > Control Panel
> Add/Remove Programs. All of these conditions _must_ be met for the
uninstall option to be available.
Otherwise:
How to Manually Remove Win XP and Restore Win9x
http://support.microsoft.com/default...;EN-US;q314052
cheers