Three good — and free — anti-virus programs:
Avira AntiVir PersonalEdition Classic
We use Avira, and it seems to work just fine. You don’t have to pay for the latest and greatest commercial anti-virus program to be adequately protected. As long as you’re running (and updating) something, you’re ahead of the game.
UPDATE (08/09/2007): AOL is no longer offering Active Virus Shield. They now offer McAfee Virus Scan Plus-Special edition from AOL. It’s still free, but you’ll need an AOL email account (also free).
