I was going to say the same people still use IE ?
Firefox is so much better.
actually, in my experience IE9 is far better than any Firefox version i've tried in the last year or so.
especially conecerning usability and stability (as for security: it seems reasonably safe, but as always, the user is the biggest threat to the systems security).
i'm using chrome btw, imho pretty much the best of both worlds with very few downsides. haven't tried opera in at least 8 years though.