A. The Internet Connection Firewall in Windows XP cannot protect against viruses that spread through e-mail, such as Trojan horses, which masquerade as helpful or benign software and trick you into opening or downloading them. The firewall cannot prevent spam or pop-up ads. The firewall will not prevent access to an otherwise unsecured wireless network. However, the firewall helps to protect the computers on your network, so if an intruder were to gain access to your network, he or she could not access your personal computer.