Hiya,
If this is on UNIX
1. sp_dropserver and drop the XP server(to clear entries from sysservers).
2. Remove entries from the interfaces file.
3. Delete the RUN Server file for Xp Server(not necessary)
For NT
MAKING a registry backup is recommended(Just in case)
All the above plus
4. Open Regedit and browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es
Here you'll find a key for <SERVERNAME>_XP, delete that key.
Cheers
Willy