SMP is probably one of the reasons Linux is so beloved in research, Windows may have caught up there somewhat, but it wasn't too long ago when you had to pay extra for a version of Windows that would allow you to use a second processor. Windows isn't even an also-ran in supercomputers, which is a shame really. Also being able to have farms of Linux boxes without fussing about with Windows licenses.

Networking is another. Windows at least used to have a bunch of different crippleware SKUs with differing networking abilities

Filesystems, Linux supports tons of them out of the box.