It is absolutely baffling to me at how invested people get in one OS or the other. I run a Windows Server 2003/XP workstation environment at home, own and use a MacBook, and run about six different distros of Linux. Each has their strong points and weaknesses depending on the task, and all have their place. Where the idea came from that one must use and show total devotion to a single one I have no idea.
Maybe it comes from Microsoft's business model (and to a lesser extent reactions against it). I say to a lesser extent because those of us who hate MS for lack of attention to security, lack of stability (admittedly less of a problem on their newer stuff), the fact that nearly every default setting on nearly every MS product assumes the user is an idiot (and is, thus, usually idiotic), or any of the other host reasons folks have, usually aren't one-OS partisans, we usually are happy with both Linux (in multiple flavors) and Mac OS X and, for that matter, with Unix.