For one thing, IE 8 is arguably a more secure browser than Firefox due to its use of low-integrity process isolation on Windows Vista and 7. It's also more stable than Firefox in my experience, probably because of the way it isolates browser windows into separate processes.

And now IE 9 has a rendering engine that's at least equal to Firefox's. It lags behind Firefox's user interface in some respects (customization, built-in spell check), but it feels much faster, and it doesn't bog down over a long browsing session like Firefox does (again thanks to isolated browser processes – now one for each tab, just like Chrome).

For my part, I still think Chrome is superior to both IE and Firefox for general web browsing, but these days I certainly wouldn't look at someone funny for choosing IE. It may just take a little while for the folk knowledge that "IE suxors!" to catch up to the new reality.