I just tried AVG on my Win8 64bit machine and soon it crashed with blue screen. I could not simply uninstall it as win8 was crashing and restarting over and over. So I had to go to safe mode and stop AVG services as I could not do it from Task manager. Then restarted and uninstalled AVG. Moreover AVG turns off Windows Defender so I had to turn it on again. My recommendation - if you are on win8 stay with windows defender.