In the early 90's, there was a multitude of computing platforms to chose from, and Windows was considered no more than a graphical shell on top of DOS. Amiga, Atari, Macintosh, OS/2, RiscOS and several others were all contending for a slice of the cake, but by '97 most alternatives had either gone bankrupt or forced into small nieche markets.
Obviously Microsoft had nothing to do with the fact that most of those pretty much died due to their own failures, but many, many people blamed Microsoft for using their OEM deals to push the other players out and thereby killing off their favourite platform. When Microsoft started using seriously anti-competitive behaviour when they pushed Explorer with Windows, they also forced a feature race with Netscape (who ultimately lost, as we all know), and that race was the last nail in the coffin for the alternative platforms. There were no open source web browsers back then, and commercial alternatives for platforms like the Amiga simply couldn't keep up. Explorer became a killer app, and Windows pretty much took it all, apart from Apple which managed to survive because of Microsoft funding. And boy, those Amiga and Atari users can be rabid about Microsoft. I know. I used to be one of them. :D