Alex's points are spot on. I can find no dead set, definate reason why people STILL use Internet Explorer. All I hear is stuff like "Oh, it's too different" or some other lame excuse.
I'm sorry, but I WON'T support a browser that does not conform to Internet standards. These standards are set by the W3C (the creators of the Web, essentially). Why do you think pages that render fine in IE look totally fucked in Opera or FireFox? Because the page doesn't conform to the standards and as such, Opera and FF read it as faulty code (as they should).
I certainly hope that people who still use IE are doing so after they've tested Opera and/or FireFox for an extensive period of time. If you haven't, then you are COMPLETELY wrong. I don't care what the hell you say, but a two-day trial is utter bullshit.
By the way, did you know that a while ago, Microsoft setup the Hotmail page in such a way that if an Opera user was detected, the server would send a different version of the site to the user? This prevented us from doing a few things, the most famous being the emptying of the Junk E-Mail box. Don't believe me? Wikipedia it. A couple of Opera dev's found out, which forced M$ to change the site.