[SEJeff]

Depends on your definition of success really. Linux beats the living snot out of windows in high performance computing and supercomputers. It also beats the snot out of windows in embedded and mobile / tablets because it is so much easier for manufacturers to adapt it for their own needs. What is your definition of success? Linux never tried hard enough with desktops I think. Canonical's Ubuntu is trying awful hard to make Linux desktops relevant (which is cool) but even they have mostly ceded that fight and are going after the more viable mobile.

Ever bought a smart tv like the Sony Bravia or basically any of the nice Samsung TVs? Linux as well. How about a home router? Many of those are Linux. I'll go out on a limb and say there are a lot more Linux devices than Windows total (primarily due to the plethora of embedded and mobile).