I think the best is common sense. Anti Virus only tries to get rid of something you already have, so just dont let it in.
I'm not trying to be smart btw, but theres a wider confusion on the actual way that we get Viruses, spyware and trojans.
If you learn about them you will know how to stop it.
I only run Windows firewall and Ad-aware Pro i never get anything. I altered my cookie handling too so i dont get spyware. As long as you have a firewall, dont open unsure attachments and be careful then all should be well.
When all that falls flat on its face theres always Bitdefender haha.
Oh i also have Stinger, a stand alone scanner.