Dave Massey from Microsoft says that IE is not a part of the OS. I would agree, in the sense that it does not run as part of the OS kernel. However, the issue is that the HTML rendering component that IE provides is used by so many applications on Windows, including several provided by Microsoft. The tight coupling of the IE HTML control with so many applications is what makes IE a de facto part of the OS. If Microsoft were really serious about decoupling Windows from IE, they would provide a rendering component API that could be implemented by using Gecko or KHTML. Of course, Microsoft's dirty little secret is that IE helps to tie people to Windows, so they have no motivation to fix the situation.