Opera was much quicker than IE, but it's proprietary, closed-source, and the free version has ads.

FireFox is a fork off of Mozilla, it's been very stable, has tabbed browsing, pop-up suppression, better security and control than IE, it's about as fast as Opera (as far as I can tell), is open source and free, and runs on multiple platforms. As a professional programmer, that last is important to me, as it means that I can use the same tools in Linux at home and Windows in the workplace. You can get it at mozilla.org- be careful to get a stable version for your first experimentation, not the latest Beta. Most people are up and running with it in 15 minutes, and in 15 days won't go back.

There are some sites (notably those composed with MS FrontPage extensions, that is, MS proprietary "extensions" (lock-ins) to HTML), that seem to only work with IE... but the only way we're ever going to get away from that is to get away from IE and complain to the people who put up such sites.