A few weeks ago, I wrote that I had moved back to using ClamWin as my antivirus of choice because AVG was no longer offering a free version of their antivirus software. A couple people have written in to correct me on this, pointing me to this document.
It turns out that the free version of AVG that I was using (version 7.1) was simply being discontinued and version 7.5 was taking its place. There is a free version of AVG Anti-Virus Free Edition 7.5.
I would like to thank both Marc and Kirk for pointing this out.