You should either be using ICS or a router, not both.
Connectivity:
1. Direcway Internet connection----router WAN port
2. PC (XP and Me)----router LAN ports 1,2,3 etc.
Disable your XP's ICS. 192.168.0.X is your internal IP address range. You can check your external/Internet IP address at http://netdept.com/ipandhost.jsp This external IP should not be assigned to any PC.
Thanks.