Well, the first time I remember being exposed to computer viruses was with my Apple computers, and not the Windows computers. There was a virus that was accidentally put on a CD that came from MacHome or MacWorld Magazine. So I was exposed to that computer virus. And in addition I received a notification of a possible computer virus another time. So strange as it may seem, at least as far as I can remember, I experienced Mac viruses BEFORE I was exposed to Windows viruses! Of course, that was back in the days of the older Mac operating systems.
I think Mac OS X is safer, but I defintitely do not think it is invincible to attack. That has already been demonstrated. And some Mac applications seem to be definitely weak when it comes to security. So I think anybody who has a Mac should use a standard account rather than an administrator account, use good passwords, be sure the firewall is turned on, and get an antivirus program. There is no excuse for not having an antivirus program, because there are even free ones available, such as one from Sophos, and also ClamAV (or ClamXAV) and iAntivirus. If Mac people do even this much, it will buy them some time. It may seem bad to say this, but let the people who do not even know how to turn the firewall on get attacked first.