Re: "leap second"
Microsoft is not exactly a stranger to leap time problems either.
Linux, like any software, has bugs, but Windows is endemically and fundamentally flawed in so many ways, from its grossly over-engineered design, random and inexplicably dysfunctional behaviour, to its afterthought "security" - with little concept of proper privilege separation / law of least required privileges, that the idea of using it for anything even remotely critical is just silly, and actually potentially dangerous.
Then there's the fact that any given *nix is not homogeneous, even within a single distro, so a "problem" that affects one version of one component on one release of one distro won't necessarily bring World + Dog to its knees, whereas a single fubar on e.g. Windows XP (still the most common OS - in that tiny segment of the computing market called "the desktop", anyway) can shut down a significant portion of entire countries (e.g. the recent Internet Blackout).
There's a lot to be said for a heterogeneous infrastructure, doubly so if one completely eliminates Windows from the equation. There's even more to be said for having access to the source, so you don't have to wait for some poorly-motivated vendor to "fix" some crippling issue on some Tuesday in the distant future.
Server == *nix. Period. It wrote the book. Anything else is just a toy, and Windows is the sort of toy you'd expect to win at a carnival ... if you were really unlucky. It might work as a game system (FSVO: "work"), but even there I think you'd probably be better off with a console ... no DRM, virus or driver issues to contend with.
Really, the only reason anyone uses Windows at all is because consumers are force-fed it by OEMs, mainly thanks to some historically dodgy deals (and some not so historical, I'm sure). Business customers don't have that excuse, they just have clueless pointy-hairs making uninformed decisions based on buzzword-bingo propaganda. Or at least 40% of them do, according to Ballmer, anyway. The rest avoid Windows like the plague.