Don't kid yourself. No AV program can really protect you. By the time the AV program owners send the updated definition files around, millions of computers have already been infected with the newest and latest virus. And those buggers get more sophisticated every day.

We install AV programs for our peace of mind - but in reality they are pretty useless. What helps is:

1. Discipline - don't click on things you don't know.
2. Run your internet activity in a virtual Linux machine. There you are a LOT less likely to get attacked
3. or run the browser in a Sandbox and scan all items you downloaded before putting it on your system
4. Make frequent images so that you can back paddle in case of a crisis