Not to derail the thread, but I'm having problems getting players to connect to my server when I'm running in Windows 7x64. Just gives them the "Connecting" message forever.
I would guess a 64-bit component that either (a) doesnt work properly, or (b) doesn't work the way the Java virtual machine expects it to.
Since you're not getting a completed network connection, I'd guess something in the network stack.
I just tried connecting over LAN on the same machine, and no problem. It's just when I try to go through my external IP that I have the problem.
My internal IP is the same for Vista and Windows 7, so forwarding shouldn't be the issue, and I can connect to myself through the Maptools dialog when I'm in Vista.