Magoo - I used to use AVG. The problem I had was it 'quarantines' the virus, which is then backed up into the system restore. Not really a problem, unless other things go wrong, or the virus is actually a key, and it can cause havoc.
I downloaded Avast and ran it and it spazzed for about 3 hours getting rid of all the stuff that AVG had a) quarantined, and b) missed.
I'm on broadband and it looks for updates several times a day and downloads in the background.
But if you like AVG - live well and prosper
a lot of it boils down to personal preference. I love Avast. Yak does not.