It has long been my experience that Macs suffer less hacking and security violations because, frankly, the hackers don't waste their time with them.
One of the major objectives for a hacker is the thrill. Combine that with the fact that most members of the delinqent persuasion are stereotypically lazy, and it starts to make sense that a hacker is going to focus on the biggest target in order to obtain the biggest bang for the buck. That equates to targeting a windows operating system rather than a Mac OS.
When you change a hacker's focus from one of entertainment to that of financial gain, where do you suppose the largest percentage of financial information is stored? Does the hacker write a script for a PC or a Mac?
Finally, if you put yourself in the shoes of an up-and-coming hacker, what OS target would support the biggest library of tools and resources for your hacking education? Windows or Mac?
Again, in my opinion, the Mac OS is not necessarilly more secure, but rather an unattractive target.