@mgr:
… As good as UPnP can help you get "unwilling" equipment to open ports: there is a hidden danger in using UPnP though: If you catch a malware program one way or another that program is able to silently open a port for its own use by using UPnP system-calls, not only in your firewall but also in your router for outgoing and incoming traffic which enables this "pilot" malware to download a really harmful program to your computer without the knowledge of your router, your "security system" / firewall and, worst, your own knowledge!!!
I admit it is easy to use UPnP to open ports in your equipment - but be sure to log such attempts (if at all possible) and watch that log carefully!
I recommend though to have at least one secure "last barrier" which will not react on UPnP and handle that barrier (in my case my external router to the internet) manually. Call my paranoid, but I'm very cautious about the security of my LAN - that pays off too - I had several intrusion attempts in the last couple of years but I always could delete the regarding software without harm being done 
For this very reason I would suggest also using a firewall such as ZoneAlarm. It will allow you to lock your machine down in such a manner that upon malware attacks, the firewall must first be configured to allow the program, port, etc prior to it being able to make the connection.
