I've been wanting to purchase an anti-virus package since I built my new box, but I remember friends telling me that they take over your system. I tried a demo of McAffee and hated it and was wondering what everyone uses. I'd like something that doesn't run in the background. When I think something could be fishy, I can just hit scan, and that's all. Also, I want something that automatically updates it's virus definitions. Can you guys post your thoughts?