AVG Antivirus
Offering a rock-solid protection AVG is THE BEST FREE ANTIVIRUS from this test. It has a very good deffinition update system,uses little system resources and a full time protection utility with "on-access" file scanner and e-mail scanner.

The program doesn't tax your system when scanning or when running in the background and always proved effective in our tests. This app's interface can't be described as beautiful, yet it is mostly simple to navigate. During the full system scan it has detected both of our major threats on the test computer.

You can download AVG Free Antivirusfrom here.