Change xp pro file associations for domain users (SBS 2003) ???

Hi!

I recently installed a SBS 2003 server with a few XP Pro clients,
before that the clients were using a LINUX SAMBA server.

since the change to SBS 2003, the possibility to change file
associations is disabled
within windows explorer for domain users.
I can change associations via the administrator account, but then this
assiociation
isnt available for the domain-users, this seems to be part of the
profile ?!

we dont use roaming profiles.

any help on how to change existing fiel associations for SBS 2003
domain users
on XP Pro would be greatly appreciated, thanx in advance!

regards,
Hans