Exactly! Why would anyone want to use the bug-infested security hazard known as IE when Firefox works so well?!
Not to trumpet IE, but FireFox still has tons of problems. It trashes its profiles regularly, must be WIPED OUT if you want to re-install it, or else damaged profiles will be retained, the download manager sucks, it crashes, extensions are always having version conflicts, bad extentions blow up the whole browser, it still suffers from an annoying "Sticky Alt Key" bug that has been in the browser since 0.8, the JavaScript debugger actually ignores certain critical errors... etc., etc., etc...
Trivial bugs just don't get fixed, at least not in the Win32 version. Also, I have to wait for my extensions to be updated before I can get a FireFox update, so new versions are hardly welcome. I've had to re-install it, like, twenty times since I started using it a couple years ago. IE never gave me much trouble other than ActiveX, which I have disabled. If only Flash wasn't implemented as an ActiveX control, I'd use IE more often.
Oh yeah, and now that FireFox is popular, pop-up blocking doesn't work, anymore, and I've had more than one site nag me to install an XPI or two. Security through obscurity no longer applies.
I have FireFox as my default browser, as it is good, but I wish people would point out its faults more often. It has
plenty of design flaws of its own.
As for Opera, it's ugly and the GUI is stupid. It does, however, have a phenominal JavaScript debugger. If a web page works with Opera, it'll work with anything. ;-)