i'm assuming your setup is like this: internet > xp sp2 pc > router > other pc's for the shared connection in windows xp, right click the connection, go to "properties", and on the "advanced" tab, under "internet connection sharing" click "settings", from here you can setup ports to forward to the router, so as long as you know the router's ip just add the ports you need forwarded e.g. tick the "web server" option on the list, and then type in the ip of the router where it would probably say the windows xp sp2 computer's name. for my network i have: internet > router > smoothwall (firewall pc) > switch > my pc's i simply have dmz setup on the router, pointing at the smoothwall, then from the smoothwall i have port forwarding for desired ports to whichever computer i need them to