Ive been using Comodo internet suite for a while now and it includes a pretty good anti virus plus firewall totally free. very nice!
I usually don't use any AV anymore, but that's just because I've been around so long I'm pretty able to spot and examine anything suspect before it can infect me. But I do still install some here and there to see how they are. Lately I've been liking F-Secure and comodo. I like the comodo firewall, but since it also comes with an av, it's handy too.