Symantec knows who butters their bread
It's in their interest to have lots and lots of virii-infected computers, making users run into their arms for viral protection. If people use operating systems less prone to viruses, or browsers that don't infect computers as easily, Symantec doesn't get as much bang for the buck out of their "buy our software or die" (tm) marketing strategy.
So why am I not surprised that Symantec has just released "reports" claiming that FireFox is more vulnerable than IE and OS X is due to be nailed by viruses. Is it because people running FireFox and OS X are less likely to buy their antivirus and firewall software? Does Symantec want a world full of Windows XP / Internet Explorer users that they can intimidate into purchasing their software?
What's the next "report" going to claim? Linux is less secure than Windows?