In the game.cfg there are standard ports. 32768. Some routers have problems dealing with using the same port number when hosting and playing from.
Hence the no connect with your local machine.
There is 5 numbers that all need to be changed to match the same one.
Try adjusting your playing pc to something like 32780. Remember all 5 of the numbers matching below must be the same or you can't connect to novalogic or you may bet a connection error. If this doesnt work and you want to go back all you have to do is delete the game.cfg and start the game up. It will re create the game.cfg to default settings.
mpnovaworldportmin = "32768"
mpnovaworldportmax = "65535"
mpnovaworldportdelta = "1"
mpnovaworldportrandom = "0"
mpnovaworldlanenumsessionportmin = "32768"
mpnovaworldlanenumsessionportmax = "65535"
mpnovaworldlanenumsessionportdelta = "1"
mplanserverportmin = "32768"
mplanserverportmax = "32787"
mplanserverportdelta = "1"
mplanclientportmin = "32768"
mplanclientportmax = "65535"
mplanclientportdelta = "1"
mplanclientportrandom = "0"
mplanservertojoinportmin = "32768"
mplanservertojoinportmax = "32787"
This should fix the routing issue and allow you to connect to your server. Has nothing to do with windows 7 as this problem would duplicated on xp.