Pretty much the only people who have a vested interest in viruses are anti virus manufacturers.

Personally I don't use a resident virus scanner, I have AVG there to do a scan when I feel like it. As long as you're not stupid with your surfing habits then there isn't much threat.

Same thing with a firewall - the windows one is perfectly good enough to protect you, and if you use a router which is set up correctly again there isn't much of a threat!