Well I like to use the free version of avast. I also use malware bytes, and super anti-spyware for quick scan once in a while. Once in a while I get one of those annoying fake antivirus software viruses but they're not too hard to remove.
Ya I don't really believe the world is going to end just because the Mayan calendar is going to end. I think it is more reputable then the other doomsday predictions though, I'll give it that.