As much as I hate to say it, any OS that runs on 90%+ of the desktop computers in the world cannot be considered "non-standard". Propriatary, perhaps, but it is also a standard.

I keep hearing this statistic about how Windows runs on 90+% of desktop computers.

For some reason, I find it very difficult to find any numbers indicating what percetage of world computers are classified as desktop computers... I dunno, maybe I'm wrong to think that maybe MicroSoft's stuff runs on a minority of the world's computers, but I can't find anything to confirm nor deny.