I figured out a trick that works to recover XP User accounts when doing a clean install of XP but i have never attempted to recover a 2000 Account to XP.
1. Locate the old user profiles in c:\documents and settings\" and rename them all by adding something like "_old" to their names.
2. Create the new user from the XP control panel
3. Log off current user and log onto the newly created user. During the first login windows will recreate the users folder in c:\documents and settings\". Make note of the newly created folder
4. Log off the new user and log back onto any other administrator account
5. Delete the new folder windows created for the user at logon in step 3
6. Rename the folder from step 1 again to the name of the new folder you just deleted in step 3.
This works every time for me when restoring xp accounts. It wouldnt hurt to try in your case though. I would be very interested if it works or not.