I don't really understand this and havn't tried to do this myself but the easiest way looks to be this.
What I needed to do was this:
2k & XP folder: \\server\profileshare\enduserfolder
Create a new folder called \\server\profileshare\enduserfolder.v2
Apply permissions, don't inhereit, delete "authenticated users", add your end loser up to "modify"...full if you really want to
Done, it creates the profile and uses that new .v2 folder without incident. Apparently Vista and Win 7 use that .v2 profile folder path. Good idea, you guys at M$ are slick ;-)