Yes, you can have a windows Nt Server 4.0 with win 2000 Clients. Yes, you are right when you try to join the domain, You can't Join Windows 2000 Client to a Windows NT Domain.You have this problem sometimes.
Reason:- If your only protocol is TCP/IP and you disabled NetBIOS over TCP/IP, that is probably your problem. This can also be caused by some 3rd party DNS servers, that do not support SRV records.
Solution:-
To enable NetBIOS over TCP/IP:
1. Start / Settings / Network and Dial-up Connections.
2. Right-click Local Area Connection and press Properties.
3. Select Internet Protocol (TCP/IP) and press Properties / Adsvanced / Wins.
4. Click Enable NetBIOS over TCP/IP.
5. Press OK until you are out. You can ignore the 'empty primary WINS address' message.
If you don't want to enable NetBIOS over TCP/IP, you could install NetBEUI on the clients and the server.
Thanks,
Jasjeet Singh