I'm going to have to say it's Nod32 hands down. Runs very light (takes up very little resources). Has very good detection rate, I've downloaded some pretty crazy things in my time, and its caught them all.
Also, A virtual machine is another great idea, I use a couple of them actually. Very easy to set up especially if your running windows 7 professional.
Also, A virtual machine is another great idea, I use a couple of them actually. Very easy to set up especially if your running windows 7 professional.