NT4 servers in 2003 AD domain

I am migrating to Windows 2003 Active Directory for my single location company. I am testing out the upgrade and have hit a snag. I have an NT4 file server named ERP1 (not a DC) which is not accessible from my test network. My test network includes a Windows 2003 server DC upgraded from a former PDC. I have both a Win2000 and an NT4 workstation from which I have mapped drive to a share on ERP1. Neither system can access the fileshare on ERP1. What do I need to do to make the NT4 server shares accessible to the AD network?

Thanks,
Bob