Windows 7: Question about port forwarding for a private wow server

I've got a friend that approached me earlier today with the idea of running his own private wow server. While I know this is feasible, though maybe not with the hardware he is running, we are at a disagreement on whether or not it is possible for him to forward ports specifically for his computer and leave the rest of his household electronics unaffected by the security lapse inherent in doing so. Is it possible to forward ports for certain computers on a network and keep them closed for others?

Yes, When you forward a port in a router you have to specify the IP address of the PC that the port is forward to. This doesn't mean that once someone gets in through the WoW server port they cant try to access other things.