I've always thought it was funny when someone would try to sell me on macs by saying there are less bugs and viruses on them. You have to remind them that if Apple had 90% of the business computer market that wouldn't be true anymore. Apple's best security is the fact that far fewer people buy their products than they do Microsoft's.
A really common response to that is, "well, malware share on Macs should track the market share of Macs; it doesn't, ergo Macs are more secure".
This is, of course, silly. We haven't hit "peak oil" for Windows infections. A new Windows worm still pays off wildly better than a Mac worm; writing Mac malware is economically irrational.
But, at the moment, there are less viruses on them for precisely that reason. Security through popularity is working for the time being. That and linux/unix/os x have the principal of least privileges working for them too.
No, they don't. We can go through the motions on this "OS X has a better privilege model than Windows" argument, but I know how it'll end: malware doesn't need (or even want) root to win.
