A few words on IE/Windows bundling issue

So it seems a good number of people has been claiming Microsoft having an unfair advatnage with their browser as it’s pre-installed with Windows. But, oh well, since it’s the same company who’s making the OS too, that’s an advantage that should go to their credit right? I mean, what about Safari on Mac? Or even the browser that comes in iPhone? Toyota cars had stereo systems made by them built into the cars, but I doubt if that was considered as an unfair advantage. And if this allegation is right today, what stops another company to point the same about Windows Media Player, Outlook Express, Messenger – and pretty much every other application that comes with Windows? I have a lot to learn about business laws but I’m really confused on this: where do we actually draw the line for bundled apps anyway?