Have Used Alot of Atni-Virus Programs Myself.
I have recommended a few out.
And StopZilla is one I do would recommend.
I have seen this one Stop a virus that some of the others will not.
Anti-Virus programs To me are more of how user friendly they are. Just like any operating system Some people Like XP or Vista and even Windows 7
StopZilla is compatiable with all mentioned windows above.
Just simply Click on the Above picture and See how it works on your system
