Why? Because most people don't want Microsoft looking inside their computer. Last I heard, IE 7 will incorporate an anti-phishing layer that when you go to a website, will send that URL to Microsoft to determine if that site has been tagged as a Phishing sit. With Microsoft admitting to a backdoor in IIS-5 a few years ago, I am not to excited about this crap and all it takes is for that to leak out to Johnny Q. Public and I am sure they will feel much better about installing some other browser. By the way, I got that bit of info right from CNN (who use Firefox as I have found out as well).
