router to playstation 2 can't connect

i have a main pc hooked up to roadrunner cable and using win xp. have a linksys router wrt54g connected to modem and modem to pc. second pc has pci adapter wmp54g card and is connected wireless to the internet with no problem. my son has a play station 2 in his room and is running a cable from the router to his game, wanting to play games on the internet but can't connect. anyone have any solutions?