> If I want Firefox then wouldn't I have to install IE first
No. Most magazines come with a DVD filled with umpteen different browsers. Also, how many people only have access to one PC nowadays? It's a very simple matter to download (as an example) the setup.exe for firefox from another PC in the house or a friends computer, stick it on a USB key and then run it after installing Windows 7.
Although I think the whole thing is ridiculous. No one is making Apple remove Safari from OSX. If a user REALLY wants a different browser on the PC before they buy it there are any number of PC builders who, I'm sure, would be only too happy to stick Opera/Firefox or whatever on there to get a sale.
For people who know nothing about PC's, Microsoft bundles a browser. For those of us who know what we're doing, the choice is there. I really don't get where the problem is?