My work computer actually has McAfee on it, which I've disabled through the registry. Don't like how slow it makes my computer.
Education, people! It's better than buying useless feel-good software.
A cold virus's best strategy, for example, is to keep you awake coughing so your immune system is weak, make you sneeze and cough and have a runny nose so you spread germs, etc. But it shouldn't kill you, especially not before you pass it on. I've heard (did I read it in Guns, Germs and Steel?) that syphillis used to be more deadly, but that it got milder as an adaptive strategy.
Likewise, computer viruses probably have a pain threshold they shouldn't pass. If they can do their masters' bidding without hacking you off so bad that you format the computer, they'll be more successful.
Possibly unwarranted conclusion: computer viruses are now widespread precisely because they're Not That Bad.
So, are they worse than antivirus software? A lot of non-geeks may be asking themselves that question today. "Dang, we got a virus one time, but it didn't keep the computer from BOOTing!"
McAfee has just demonstrated a computer autoimmune disease.
Does anyone recall the Michelangelo virus? One of the virus detection programs special release for that wiped the boot sector of every drive it was installed on. I think it is fair to say that in that case, the anti caused more monetary loss that the virus.