I could go on and on about the differences between things such as Windows and what I've heard about the Mac OS, but there's one thing I KNOW as a developer of more than 20 years of experience - MS has done a SUPERB job of creating tools and APIs for developers to do some serious work, even down to creating multiple languages that are all compiled into the same intermediate language. Basic damned near as fast (if not actually AS fast) as C# - that means a lot to a lot of people. This allows for more developers to create more varied apps easier than any other operating system in the world. In addition, there are millions of third-party tools available that all use the same efficient framework and extends MS' original work vastly.