Well, to start, you could simply run a network tool to view the traffic. That will tell you immediately what exchange, if any, is happening between machines. Wireshark or tcpdump are available for both operating systems
I have been sufferring from the same issue but not just restricted to Win 7 machines - it appears to be any that I try to connect.
I'm running OS X Server ML.
Have installed Wireshark on a test windows xp laptop.
Not 100% sure which protocol to look out for - any further help on what I should be lookking out for / expecting to see please?
just a quick update...
Got the correct Wireshark filter to show DCHP traffic and I can see the server making a DCHP offer and the laptop making a DCHP request/DCHP discover
Why can't they make a connection? This goes beyond my current knowledge so apologies in adance!