When you need a car for getting places and a truck for moving things, and you can afford both, you don't need to choose between one or the other. You can have both, and use each for what you need it for. Operating systems are not a life-choice; they do not demand exclusive relationships.
* my cheap TV card only worked on Windows reliably
* most cool games did not work on WINE (and Unreal Tournament can become boring after some time)
* Webcam did not work on Linux (in fact until 2 or 3 years this was still a big issue)
* One word: MS Office
* many websites did only work on Windows
Yes and that's when you dual boot. So when listening to music and web surfing on Linux, I couldn't write a letter on Linux. Because StarOffice/OpenOffice had significantly lower quality than MS Office during that time. I couldn't play a video game and afterwards browse through my MP3 collection.
In such a situation you will almost naturally stay with the system that has most features for you, i.e. Windows here.
Today's "migrators" are lucky because emulator technology has evolved a lot and modern consumer (multi-core!) CPUs have some serious virtualization support. Moreover many applications moved to the Web. 10 years ago the only thing genuinly cross platform where some super ugly Java apps.
By the way, I am a Linux, OS X and Windows user. However the stuff I use works (luckily) on all 3 OSs. (Ok, I'm honest, not on Windows. ;)) Nowadays I enjoy switching computers and OSs, however this is only possible because I use Unix stuff and that just works almost everywhere.
Very happy with this poly-OS setup.