AVG is probably at the top of the class when it comes to FREE av. If you want top class protection and are willing to pay for it then give Kaspersky a go. Kaspersky updates its virus definition every hour and catches NEARLY everything. Fact is though that no av can be 100%, as new virus`s are released then somebody is going to get caught with their pants down before virus definitions are circulated for it. Best form of defence is if it don`t feel right then even if your av says it`s ok, don`t open it.