join servers to a domain in a secure network

Hi everyone,

I have this problem.

We have a few servers in a data center and i want to join the other servers to the main Domain Server.

Server is running Windows Server 2003 SBS and the client machines are running Windows XP

The only problem is, none of the servers can see each other if you type in the computer name.

Can someone please give me advise on how to join the servers to my main domain