I assure you, this situation is far, far graver than any of the rest of you seem to know. As much guesswork as it is figuring out who runs what, I'm going to take this recent Ars Technica article and give both Apple and Linux the benefit of the doubt. I'll hedge their numbers up to 4% desktop market share for Apple, and 2% for Linux. That leaves Windows at a mere 94%. These figures match our conventional wisdom pretty accurately.