How to Join a Win 7 to a domine

am not able to join to my domain. We just installed a new Win7 ultimate 64bit- When ever am trying to add to the Domain am getting an error message ” An attempt to resolve the DNS name of the domain controller in the domain has failed. Please verify this client is configured to reach a DNS server that can resolve DNS names in the target domain”
My Win 7 IP
192.168.0.20
Default Gateway -192.168.0.1 (same as Router)
DNS -192.168.0.200 (Server IP)

Server 2003 Small business
192.168.0.200
Default gateway-192.168.0.1
DNS 212.118.0.1
212.118.0.2

Please some on help me..