7 years ago (7 years after I left Microsoft), Apple has introduced iPhone. As the result, I have switched my main machine from Windows to Mac. Since then, I have *completely* moved away from Microsoft platforms, and just use either open platforms or platforms provided by Apple or Google.
The combination of two fasts, (1) Mac was *necessary* to develop iPhone applications, and (2) Mac was *better* machine to develop software on open platforms, turned Mac into the de facto standard for developers and made Windows irrelevant.