The best Antivirus around for me is AVG. AVG sets itself apart from many other Antivirus with realibility, stability and updatability. And you can get one for free. It also not messes-up with your registry during installation and uninstallation. It detected almost every viruses around with breeze. It's interface is simpler though. I've tried paid antivirus programs like Norton, MCaffee, Panda and PC-Cillin but AVG still impresses on me more. On Norton, though, one nice feature is the ability to scan through zip files in real-time. The negative side here though is it utilizes much of your PC resources during scans. 
