My client has just installed a new Windows 2003 server, how do I set it up to access the workgroup that has all the other machines on it ( a mix of XP and Windows 2000 boxes).

Currently the 2003 machine shows in Network Neighbourhood as a separate group (domain?). None of those machines can see the new server in Network Neighbourhood, just the other machines in their workgroup.

I am new to this server stuff so forgive me if this is a basic question that I should know. I tried to find the answer in the help topics but am now more confused than before.