Here, a bit for the ones who like to read a wall of text
When I got my first PC ever, it came with this shit called "Avast", and it disappointed me, since I got a virus which made my PC restart every 5 minutes, and Avast was supposed to delete the virused file, and as soon as I restarted the file was there again o.O
Then I tried Panda, I loved and used that antivirus for over 2 years, deleted all the viruses and actually WAS effective, but bad thing about it is it needs hell of a good PC or your performance (specially start) will be shitty.
I've tried most of antiviruses in that list, and almost none satisfied my "needs", only Nod32 with is very good too, but since I'm using Windows 7 now (practically Vista), I don't use any, you'll barely find a potential virus when using Win Vista/7; when a virus fucks the system up I just burn the important data in a DVD and format
In conclusion, answer 10, I don't use any antivirus actually, and I typed such a lot text cause I was a bit bored