Microsoft is a monopoly in the PC market. There are no true monopolies if you want to get hyper technical. Some joe could have gone out and sold buckets of oil on the street during Standard Oil's height of power, but would that have made him competition? That Microsoft is a monopoly is in and of itself irrelevant. The fact that that monopoly is backed by unbalanced licensing terms and the US patent office, is quite relevant. Microsoft would be no threat to anyone if it couldn't patent its file formats, programming languages and network protocols. Patents are fundamentally at odds with how software is developed. Software development requires interoperability without restrictions. Free and commercial software alike have to be able to work together. That is how networking works. FR wouldn't exist if Larry Wall had taken Microsoft's approach to PERL, the government had not released control of TCP/IP to the public domain and the W3C restricted the ability to create open and commercial implementations of HTTP. If you are using Windows, you are using the BSD networking system to post to FR. Yes, that's right. Windows' networking system was taken from BSD, not written from scratch.
I don't have to get "hyper-technical" to suggest Microsoft has competitors, and that Microsoft cannot raise prices forever without their customers going elsewhere. While Microsoft currently enjoys a position of market dominance, they are not guaranteed to keep it. Microsoft is not a Standard Oil or an Alcoa Aluminium.
However, you will find that I am highly critical of some of Microsoft's business practices. They have in the past, and apparently they continue to steal software belonging to their competitors; this past month Microsoft was levied a multi-million franc fine for packaging some small French software company's software as their own. This isn't the only time they have resorted to outright theft. Mircosoft stole Stac Electronic's Stacker software that automatically compressed your hard drive in DOS 6.0. A few years before that Microsoft released Video for Windows which was nothing more than a plagerized Apple Quicktime that ran on Windows version 3.0.
When you take these incidents with their sometimes deceptive advertising, then yes I have a problem with Microsoft management. I do not think that Microsoft Corporation is a monopoly. Rather I believe that some of their upper executives are guilty of some very shady behavior. I do not believe that Microsoft could accidentially package three different competitors' software packages by mistake. This is not monopolistic behavior, it is criminal behavior, and should have been dealt with at the time.