Do you find the crippling effect that most anti virus software has on a computer's performance worth the "security" they provide? I've never been able to really tell myself its worth it, and have used my computer without "protection" for years without any problems. Jeff Atwood wrote about this a while back, taking a similar stance.

So I'm looking for some discussion on the merits and downfalls of antivirus software, and whether you personally think its worth the hassle. One point I do think is valid is that I am probably okay with not running it because I know if something goes wrong I have the ability to make it right (most of the time) but I can't really recommend the same for family as they may not be able to...