oh, and zone alarm is a firewall, but it may not tell you about ports that are opened from the inside (which is what a trojan would do). most firewalls prevent ports from being opened from outside. to detect them being opened from the inside, you would need to check for rootkits, and/or setup a separate IDS (Intrusion Detection System). with all that said, security is a pain in the ass, but you don't want to use a sledge-hammer to drive in a thumb-tack either.