So in a sense, UNIX now is more secure, partly because it's older, partly because it's used in scenarios where people take more care with the configuration, and partly because it's a more diverse environment. But a great part of it has to do with the fact that hackers always try to attack the platforms that offer them not only the best chance of success, but also the greatest impact. And even today with all those IOS & OS X boxes around, nothing beats Windows as the ideal target. But that may change in the future as market share changes.