I use AVG free version on all my computers at home and have not had any problems and it hasnt affected the computers speed like some of the more well known paid for versions which seem to want all the processing power.
I agree that if you want a good free antivirus you can't go wrong with AVG.
If you want to pay avoid 360 and go for Bit defender or Kaspersky, but it also depends on which OS you're running.
Pretty much all the well known anti virus packages will give adequate protection to a sensible user, no anti virus will give adequate protection to a user that just going to click allow every time it comes up with a warning.
@ Bobbisox - It would appear you have downloaded the free trial of the pay version of AVG which gives a couple of extras but is not worth the expense. Your best bet is to uninstall it using the add/remove programs feature in windows control panel and then re-install AVG ensuring you download the free version rather than the trial version.. Easy mistake to make as the site is designed to trick the unwary into downloading the trial version..
I had my machine built to spec - They installed AVG free and I never have had a problem - They also installed Malwarebytes which I run frequently and I have the Dogs Doo Dahs.
But as Chuck says if you just click when you get a warning, nothing will help you.
I mean if your anti virus pops up a warning and you just see it as an annoyance and click on allow to get rid of the warning then you may as well not have any anti virus software installed.
The best anti virus in the world is no good if the user just over rides it and doesn't let it do it's job.