I'm with the above Norton is good but far tooooo much of a resources hogger and wouldn't have it even if was free. I used most in my time Kaspersky is a good one and used it for a while but since moved on to AVG Internet Security 2012 after using the 2011 one for a while and i'm imprested by it. Anti virus software is very much like cars … each to their own. Also it depends if you want to pay for it or obtain keys from elsewhere. If your going to go for the free ones then my opinion is you won't go far wrong with AVG.