I use AVG. It has caught viruses and obliterated them. I also use something by McAffee called stinger (http://vil.nai.com/vil/stinger/). It works great also. I'm not brand loyal - I'll use whatever's free as long as it works. So far so good. Ad-aware is great too not really anti-virus but it weeds out ads that can carry trojan viruses ... I think. It finds bad stuff and gets rid of it and that's all I need to know.