PC and Xbox Live...

I have a PC and bought an Xbox 360 for my kids at Christmas, and the two systems are connected to a D-Link (DI 604)...

The PC seems to work fine, but when trying to connect the console to certain players in online games, the connection can't be made, but if a third party hosts a room, my son and the other player can connect, but can't communicate with each other. I've called D-Link, my ISP, Xbox Live...but this problem still persists...does anyone have some info, or a link to a help page?

I've heard some mention of port forwarding, or disabling the firewall in the router, to allow for any players online to connect to us.

Can this be done? Any help would be greatly appreciated.

Thank you