Here is what we need to do:
On the 2003 server check its IP address (is it gettiing it via dhcp?)
You should check gateway, dns, and wins, make sure they are the same as in the LAN.
Make sure that NetBIOS over TCP/IP is enabled as well as the services “Workstation” and “Computer browser”
Do the same thing on the other 2000 server
Can they ping each other?
Can you use a net share command to map the drive?
Is the windows firewall on the 2003 machine?
What antivirus are you running?