Cayman:
Hello and welcome to the forums.
Edit the contents of the username box when prompted, to include the machine name of the Windows 2000 machine then a backslash and then a username that you know is good on that box, like
Win2kServer\Username
PasswordForThatUser
See if that helps.
If not you may have to make some adjustments to the level of NTLM used either on the 2k Server or on the Win7 machines. Win7 uses NTLMv2 out of the box, I'm not sure about 2000 server, but that may be an issue. Try that google thing and see if you can do a little research on LmCompatibilityLevel as well as NtlmMinClientSec and NtlmMinServerSec. You may also refer to this topic and see if you find it useful at all.
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