Errr.....
With the release of MacGuard and it's variants, it shows that Macs aren't so secure. The only reason why Macs haven't been hit harder has been because the OS market share. The crackpots that create malware are aiming at Windows users as that is a bigger market share and will find the most novice uers.
But with Macs being higher priced, I suspect we won't hear the last of Mac malware because a) Apple couldn't defend the OS correctly and b) Macs cost more than PCs - so they can afford to fork over more money.
Face it. apple did badly when it came to addressing the problem. People complained in their forums [and others] and MacGuard support calls hit 25%+ on the issue and all Apple initially said was to by some anti-malware program at the app store [of which Apple gets 30% off the top]. Only after that they released an update that fixed that problem but doesn't solve the underlying problem of how the bug was manipulated.
Note the recent issue with the battery software where every one has the same default password. Malware writers can easily manipulate that issue.