I've been using and recommending AVG for a few years now, but after it updated today (2012-05-16), I'm not so sure anymore. I rebooted since avg requested it, but after working for an hour my system felt really sluggish. My browsers (FF3 and Chrome) had "AVG Do not track" sneakily installed and avgidsagent.exe was eating up 800MB of RAM!
I uninstalled the browser plugins and disabled AVG identity protection. Bad AVG! Bad!