It seems since AVG really started gaining popularity as a realistic AV scanner for everyday use, free AV scanners have been popping up all over the place. I’ve compiled a list of a few that I know about.

Avast
Avira
Panda Cloud
MS Security Essentials
AVG

I tried Panda Cloud and it works pretty well, however I think I would like to wait for a few more versions before I start trusting it a lot. Personally right now I’ve been using MS Security Essentials. It uses the same scanning engine that Forefront uses, which I’ve been pretty happy with. Plus it has relatively low resource utilization, so it doesn’t bog down your computer.

All of these are good alternatives for the standard Mcafee or Symantec. However I wouldn’t expect a free version from either of those two companies anytime soon. They have a reputation for being the two leading AV vendors out there and I don’t think that reputation is in any danger yet.