I have norton running on my machine at home with Zonealarm firewall... i haven't had any problems with those. I've also got a adsl modem/router for my broadband that has hardware firewall. When I managed to get a virus of one of my friends cd's that norton couldn't get, getting the most up to date Stinger got rid of it. If your virus protection let through something and cant get rid of it a free dose of Stinger anti-virus generally gets it.
http://vil.nai.com/vil/stinger/
Porl''
http://vil.nai.com/vil/stinger/
Porl''