The SANS Top 20 list is out and check out this one:

* Operating systems have fewer vulnerabilities that can lead to massive Internet worms. For instance, during 2002-2005, Microsoft Windows worms like Blaster, Nachi, Sasser and Zotob infected a large number of systems on the Internet. There have not been any new large-scale worms targeting Windows services since 2005. On the other hand, vulnerabilities found anti-virus, backup or other application software, can result in worms. Most notable was the worm exploiting the Symantec anti-virus buffer overflow flaw last year.

So now it's not your OS's fault you have a virus it's the anti-virus software's.

I'm only surprised it was Symantec and not McAfee. But then again Symantec would be my second pick.

(via Bruce Schneier's blog)