here is how to switch domains and keep your desktop in Windows 2k pro.

1)switch domain:
right click "my computer" -> properties -> Network Identification tab -> Properties button -> change domain.
You will be prompted to login to the domain and you will need a user/pass for that domain *not for your computer*

2)the trick to keep your desktop and settings is to login under a third username and change the "Document and Settings" directory for the newUsername to be the one that was the old username you used.

C:\Documents and Settings\newUserName to C:\Documents and Settings\newUserName01
C:\Documents and Settings\oldUserName to C:\Documents and Settings\newUserName

It is important that you are logged in as someone besides the old or new usernames.
Also any shortcuts will be lost that used C:\Documents and Settings\oldUserName in them.

*another way in xp:
system properties-> advanced tab -> user profile settings button -> copy profile button