I found this on the Major Geeks RSS feed download list. I don't know much about it, but it looks interesting. It's a free AV software that is open source which generally means it will stay free. I'll try to research it a little when I have time and update the blog.
ClamAV 0.83-7c

A completely free and open source anti-virus software package. [License: Freeware| Requires: Win All | Size: 4.1 Mb]

[via MajorGeeks.com]