There is a not so recent article that does a great job of explaining why OS X is more secure than Windows. It uses the classic “broken windows” theory of urban decay, applied to the computer realm. The extreme security of the Mac has very little to do with market share. “Windows has more viruses than OS X because more people use it” just does not work. If that were the case, you would expect a relative percentage of viruses on OS X, but the number of viruses, spyware, keyloggers, and remote-controls is not proportional to the number of computers running OS X. No, it is effectively zero (when you subtract a couple of laughable proof-of-concept “viruses” that antivirus companies produce and point to in order to drum up business.) The Mac community is pretty vocal and has zero tolerance for these kinds of shenanigans. On top of that, you can add the technical reasons: OS X has some good compartmentalized security and really has no place for viruses to hide. There is no labyrinth of registry trees. There is no way to sneak in a nefarious driver. Heck, the Unix underpinnings even prevent one from opening a low-numbered port or writing to the /bin or /etc folders without explicitly authenticating as the root user. As OS X gets more market share (that’s not an “if” statement, but a “when”), I think we will continue to see the virus/spyware/keylogger/DDoS-client count remain a constant zero.