No, I'm not an network specialist, but I don't think I would need a port forward. I've got a VPN tunnel up, and it's supposed to forward every reqest without any problems, as long as I specify the correct IP and port.
For instance, my PDA can control my MediaBridge server on my computer at home when I am at work. That's not what I'm looking for here though, (but it is amusing to start playing music for my kids when I'm not home).... ;-)
It's just like my computer is in this network, it's just that it's on another network segement. My work network is 192.168.1.XXX and at home I've got 192.168.10.XXX.
I've done a port forwarding just to see if I'm wrong, and now I can do this in my browser:
http://192.168.10.5/GetLibrary -> and the library is starting to be downloaded.
But my guess is that Media Center doesn't scan the network on other subnets, what I would like is to be able to type the actual computer name or the IP no. of the computer that is the media server, just like NetRemote can.