Computers don’t show up under Domain in Microsoft Windows Network

Hey,
When I browse to ‘My Network Places’ and click on the ‘+’ beside the domain name, I don’t see any of the computers in the domain. I get the error ‘(Domain Name) is not accessible. You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions. The list of servers for this workgroup is not currently available’

Any suggestions?
It’s on a Windows XP system. DC is Windows 2003 SBS