Most antivirus software is only useful for detecting slightly older stuff. If there's something brand new out there, you're kind of SOL. I recently dealt with a friend who got infected by one of those file encryption bugs. He had the most recent update from eset and it didn't do anything. If you're that worried about it, have a computer with a lot of personal stuff separate from your gaming computer. That way if your gaming computer gets infected, who cares.
Another option, go Linux!