Can’t connect Win XP to Win 2000 Server

I cannot connect my WIN XP to WIN 2000 Server to share files and printers. I am running WIN XP SP 2 and WIN 2000 SP 4. I also have WIN 98 Clients in my small network which are able to connet to the WIN 2000 Server. From WIN XP I can’t see the other systems and vice versa. What do I have to do on my XP machine ?