hmm...
I've been thinking about this and come to the conclusion its possible a stalemate.
If you think about it from a bog standard users point of view. This is the scene that comes to mind. You buy Windows but it doesn't have a web browser available. How do I connect to the internet? How do I download firefox or any other browser?
In all my experiance normal users are muppets... they won't think about looking for a copy of a browser on a CD (to be fair how many are available on CD/DVDs these days?) so they'd get windows which is fine but they'd have no access to the net to get anything else. People are lazy, they like to have things given to them on a silver platter and if they're not, they wont use it. For that reason alone MS have probably been the best thing to happen to the internet (in as loose a way I can possibly make it) because they've made it easy and convenient for the average person who really doesn't give a crap about how things work or whats best thing to use... to use the internet.
From there they can learn (hopefully) that there are better alternatives around and will (again hopefully) start using them.
To sum up, I guess what I'm saying is without IE being bundled with windows the internet wouldn't be as good as it is today. Yes its annoying that lots of people stick with IE, but without it they wouldn't be around to spend money online, and thats a vital driving force.