I don't believe there is a way to ban it in AH2. The firewall in Windows XP SP2 isn't granular enough to ban a single IP. It will let you allow a single IP, or a list of IPs, but it won't let you allow all IPs except the ones you don't want. Do you have a hardware firewall on your network? That may be your best option. Otherwise, you may have to install a third party firewall application on your Windows computer.