The only Anti-virus i would ever use is Nod32 from Eset it has a very light system foot print IE it wont slow down ya pc like Mcrappy or that norton rubbish does lol , i have used Avast though.....and then got rid of it cos ...again another system hog lol.AVG however was not a system hog, it just doesn't find anything lol...load of rubbish in my opinion .
so nod32 all the way it rocks...