If I am not mistaken, AVG Free do not scan for spyware. It is only available to AVG Pro or any paid edition of AVG.
KAV is not freeware so like the paid version of AVG Pro, KAV will also scan for more items.
If you wonder how KAV perform in virus test by independent researcher, see http://av-comparatives.org/
Click Comparatives at the left then select Feb. 2007 online result.
AVG Free antivirus was not tested during Feb. 2007.
What they include in the test is the paid version -- AVG anti-malware.
AVG antimalware got Advanced rating while KAV received Advanced+
AVG free is light to use but has limitation. It is one of the popular AV and it works to many users.
I decided to try the 30 day free trial of Kaspersky Anti Virus. How does it compare to Avast or AVG? Is it better, worse, or is it about the same? It seems to take longer to scan than either of the other two. I don't know that it's a bad thing, maybe just scanning more stuff. Anyone use it? Maggie