windos server 2003

Hi there,

I setup a network as follow:

1 1 comp. with win2k3 as a domain
2 4 comp with win xp as wks
3 allconnected to a router (SMC wirelles)
4 The router is connected to the dsl router.
5 Everything was working fine, until i installed the sp1 on the domain.
6 All computers (including the domain) are able to connect to the internet and are able to connect to weach other using Remote Desktop.
But, no wks is able to connect to the domain.

Any advise will be more than welcome
thanks
Hacene