I think you got the salient point by ricochet. If MS had a really superior OS, people would buy if of their own volition. At market price. They wouldn't have to be forced into it.
It is my position (arguable) that MS does NOT have a really superior OS and thus they push their product out by making it almost free to PC manufacturers as long as there is no competition. If they allowed a choice, their options would be to produce a good OS (vista does NOT qualify, and XP was obviously produced by a copraphagy) or sell a LOT cheaper. They don't allow choice so now companies have to buy the same OS multiple times for the same machine. Individuals HAVE to buy the OS if they want a mainstream machine.
There used to be laws about being able to apply that kind of pressure to the market. Neither of our opinions of the product have no bearing on the point. The point is abuse of a monopoly.