My parents were running AVG 7.5 and wound up getting infected with a fake antispyware program (virus) called AntiSpyware Master. AVG was already bugging them to upgrade, so when they got infected on top of that, it pretty much sealed the deal that AVG had to go. I installed Avast and the viruses are all cleaned off and things are functioning normally again. I very much like that Avast offers to run a boot-time virus scan after install. The one thing I don't like, though, is that it doesn't update immediately after install.
The funny part about my parents' situation was that they called both Best Buy and Circuit City's computer service and neither would come out since the machine is more than 3 years old. Money-grubbing b-stards. "We'll fix your computer for $100/hr, but only if you buy a new one!"