I haven't done a scan for viruses in the past year and a half, so I installed AVG again. Turned out clean just like before. So I second
>>2. You only need one if you download cracks and uncommon torrents and such.
Or if you're dumb enough to use IE. I checked to see if my IE was up to date on this comp and it is. And yet it STILL has holes. Even with "Protected mode" on.