I've tested most anti-viruses on client machines in the past. Most of the big names are either cumbersome or hog system resources. Norton 360 really slows down the machine and doesn't do the greatest job. Kaspersky has too many pop up settings especially for a home user. Avast has a very fast detection rate, does a good job removing viruses, will block viruses instantly when you accidentally type the wrong site has a good boot time utility as well and doesn't slow down the computer. The full package of avast imo is a little over the top imo and has issues sometimes being overly aggressive and blocking outlook etc.