I have an nForce4 board too (see first post in this thread). I just tried the following:
-turn off Simple File Sharing in Windows
-create a new location in Network preferences

Sadly neither of them helped smblient works though.
Milkman, does your whisper to chuybregts mean you know something we don't?

If anyone has any more info or even solutions then please post!

Thanks,
Mike