AVG Antivirus compatible with Windows 7 x64

I Just need to installthe Antivirus on my Windows 7 x64.What are we all using Antivirus.

ON windows 7,avast is the only one working properly. Because AVG kept shutting off Resident shield and stuff ,so I uninstalled AVG and installed Avast. It's No Problems so far.
Also my other friend use Avast as well without one problem.

For now, I'm just using the Windows Firewall since I'm using a router with a built-in hardware firewall. I have never installed a 3rd party firewall .