For the longest time I didn't have any antivirus software installed on my home computer but instead used
Housecall once or twice a week and don't remember ever getting a virus that caused any damage.
It's a free online scanner and you can put it on as many computers as you want. It's updated regularly enough and corporate-quality as far as I'm concerned. My only complaint is that because of its online nature, it can't Quarantine, but it's cleaned everything it's ever found just fine. Give it a shot!