First question, as always: Did you patch?
Second: At which stage do you have trouble?
Are you sure you have the right IP address?
Yes, I've installed the latest patch (Trials of the Luremaster). I've disabled the firewall on all machines. I'm very sure I've got the right IP Address(es).
The point at which it is not working is the connection: I enter the IP Address and press connect to session and receive the "Please wait" notification and it eventually times out to a "cannot connect" message box. I don't believe that my router is blocking ports internally over the network, but I don't know for sure. There is always the possibility that it is a Vista networking issue.