I was recently at an x-ray machine manufacturer for some training on their equipment. One system had a Linux-based control panel, the other one was Windows. Guess which one crashed while I was changing settings?
Hint: It wasn't the Linux system.
Truth be told, I work in a Windows XP shop; I know about Linux and Unix 'cause I support a lot of these systems.
But I have worked in Windows for years and had VERY few issues. Once I had Win95 / WinNT v3.5 / WinNT v4.1 multiple boot set up, and it lasted until I had to convert to W2K.
That has not always been the case for friends and coworkers - had a coworker who seemed to spend about 1 week / month rebuilding his Windows computer after fatal crashes or corruption.
But I have noticed that, if you want a reliable server, best bet is Unix or Linux.