Internet Explorer 7 has been out long enough that Windows users (like my daughter) are being prompted to upgrade. She doesn't like only being able to have "one window full-screen," but the address window will disappear when you mouse over it, and it hasn't crashed (yet).
It may say something that, upon learning that Firefox 2 was stable, I leapt at the chance to get it, while she approached Explorer 7 with more trepidation. Or it may not.
Most Firefox changes are more incremental. Adding tabs is now the default, there's a little spellcheck for Web forms, and there's a system restore, so if it does crash (and it will) you come back to the page you left, not your home page. Ad blocking is also improved, with subscriptions to a variety of pop-up blacklists.
The popularity of Firefox may best be reflected in the fact that security patches have already been released. The version being offered right now, in fact, is Version 22.214.171.124.
So far I'm still a happy Firefox user, but I can be persuaded otherwise.
Want to give that a try?