Microsoft already has such a stranglehold on the OS market that monopolising the Internet browser market would seem like a logical step. Not that I'm supporting Microsoft, mind you.
I fully support the US DoJ's efforts to try to maintain freedom of choice for consumers.
Microsoft obviously believes its in a position to bend the will of consumers to using IE4, whether they want it or not, and this sort of aggressive competitor-squashing should not be endorsed. We need fair competition to "keep the bastards honest".
If the kind of thing Microsoft is attempting is allowed to continue unchecked, next thing you know, companies will be building roads and allowing only one make of car to drive on them!