This is maybe kind of besides the point, but I think the claim that market forces allow only the best to survive is (at least in this case) flawed; if a better OS came up, would all companies abandon their existing machines, infrastructure (software, etc.), to spend money and general resources on a new system, then have to retrain all of its employees to use the new system, to learn how to use new programs? I doubt it, unless the new system was so many orders-of-magnitude better than the previous one to make the costs worth it. So Microsoft's "prowess" comes down to being there first and setting the standards, and having everyone trained to follow those standards.
Morover, the dominance of Windows (in general, the first-in) is reinforced by having software writers cater to the needs and specs of Windows in order to be able to sell to all of those trianed in the use of Windows, or else be unable to sell to just a few outliers not using Windows.
Just like if some new, better technology was developped to, say, come up with a better system of pipes for sewers, or a better road design material/technology, it is not likely that all the old technology would be dismantled in favor of the new one. The first one in gets the advantage, not the one with the best product, at least in this type of situation.
Maybe I'm bitter here, but I have followed Microsoft's advice on updates, etc., only to have my computer crash at-least once a year, then having to spend more than a week reinstalling Windows.