Sorry chaps and chapesses, I wish I hadn't said anything now.
If my opinion is worth anything, I work in a computer related industry myself. I don't claim to be an expert in computer viruses, spyware or trojans and the the like, in fact I'm not.
I am of the opinion, however, that for the average consumer any virus scanner is better than none, and AVG reviews as well as most other products out there.
I don't think most people would be under any illusion that a free version is going to be as complete as the paid for version, but for most people they will be good enough.
I have been installing AVG on PCs coming through my hands for about 5 years, and none of those machines have had any problems with viruses. Luck? Maybe, but given the internet activities of some of those people, especially those that'll click on anything and everything, I think not. Spyware was of course not covered by AVG, but was either by using Spybot or Adaware and later Microsofts own Defender, and the inclusion of spyware scanning and link filtering just reinforces my choice.
That being said, I personally use Apple computers at home, and have never installed a virus scanner on any of them, and I hope I never need to.