Beso:
Your choice to use IE is just as valid as any other choice. However most people who use IE do so only because that's what came with their computer and they're unaware of the alternatives.
Firefox 7 does seem to have fixed the problem of CPU-hogging (which was related to a piece of code which was designed to stop Firefox from crashing if, say, Flash Player crashed). Whereas there are stil loads of posts from people who find that IE won't display some website images properly.