In Windows, it's possible to replace the standard Explorer shell with another shell program, such as the CMD prompt or a custom written shell. What is less commonly known is that there is potential to use Internet Explorer as your shell in an embedded system, by taking advantage of IE's "Kiosk Mode". Check out this article on the Microsoft Support site about enabling Kiosk Mode.

Finally getting around to a project Stankdawg and I have been talking about for a while: Hacking Kiosks

IE as the shell (in Kiosk Mode)