I evaluated AVG about 10 years ago (used to evaluate anti-virus/spyware products for one of the research departments at Wright-Patterson AFB) and have never stopped using it for my personal computers. Every few years I review what is on the market and have yet to find any better than AVG. I still use the free version at home. I even disable my firewall's email scanner because AVG does a better, more thourough job of scanning while the email is being downloaded onto my system.
Although I here complaints about the major not-free anti-virus competitors quite frequently I have never heard a single, solitary complaint about AVG - free or pro.
I am in no way affiliated with Grisoft (makers of AVG) and have no stake in their success.
Their websites are: http://www.grisoft.com (for their paid versions) and http://free1.grisoft.com/doc/1 (free for personal use version - the one I use).
NOTE: There is absolutely no single software package out there that will remove 100% of the viruses, spyware, malware, trojan horses, etc. that are constantly attacking computers. In fact, many trojan horses must have custom software written specific to each variant in order to remove it. I have also downloaded and evaluated anti-spyware software only to find that the sofware itself was spyware - incorporating every dirty trick in the book such as hi-jacking the browser, inserting itself into the Hosts file, etc. So be very careful: unless you are very tech savvy or a pro, don't download "free trial" versions unless they're from reputable companies you know or it is recommended by someone you trust.
Good day and good luck.
+ Shayne