I think it's important to break out the "free" from "paid" antivirus offerings. The few times I've had an issue with AVG 8 on a paid-for copy their support has been excellent, replies within 15-20 minutes, which I'll take over a nice chat with India any day. I can't say anything about their Free support since the one time I had a problem an R&R fixed it.
We have close to 500 machines running AVG 8.0 in various corporate environments ranging from 5 to 150 users. Just leave out all the add-on BS link scanner, toolbar, firewall, etc and it works fine.
I've used 7.5/8.0 AVG free on many personal machines with no issues. AVG still hasn't stopped delivering 7.5 updates - machine I'm on still has 7.5 and still autoupdates. They say a mechanic's car is the worst maintained vehicle
FWIW we were a Symantec A/V shop for a long time. When they decided ad/spyware wasn't a "virus" and we had to resort to installing a demo of AVG/NOD32/Avast to remove a problem, or it couldn't delete an infected file that we could by using Explorer without upgrading the version, we knew it was time to move on. The licensing routines on Symantec's Corp. version is still fundamentally broken, machines drop the license and have to be manually installed. The amount of crap AVG finds that Symantec leaves behind is somewhat shocking.
Our choice of AVG was due to the least amount of trouble doing managed installs, least workstation performance impact, and a good reseller program.