Microsoft Security Essentials, from what I hear is surprisingly good. It isn't resource heavy, does pretty well with virus detection and also is free. People are loving the fact that it barely even slows start up time. I have heard that this in combination with good common sense will keep you from getting viruses.
:wcc:When life gives you lemons, don't make lemonade. Make life take the lemons back! GET MAD. I don't want your damn lemons! What am I supposed to do with these? Demand to see life's manager. Make life rue the day it thought it could give Cave Johnson lemons. Do you know who I am? I'm the man who's gonna burn your house down! With the lemons! I'm gonna get my engineers to invent a combustible lemon that BURNS YOUR HOUSE DOWN!:wcc: