Please dont use uPnP as recommended, uPnP allows software to open any port it likes on the firewall, this is INHERANTLY DANGEROUS, as if you do get a virus, it will be able to open what ever ports it wants, and leave your PC open to all manner of nastys.
Any queries .... Post a reply, and I will advise as best I can.
I am a Network Engineer
Rich, October 2007