tabbed browsing alone makes firefox worthwhile to me. plus it's power, simplicity, asthetics, etc. popup blocking standard (though the new ie apparently has that feature now too), excellent search engine default plug-in (google, ebay, yahoo, amazon, dictionary, etc all a click away on the address bar. the layout of the browser is visually pleasing, and it's all-around great in my opinion! plus the fact that it doesn't hide a cache of ALL page visit hitory usage data in hidden files practically inaccessible to the normal user (like IE does)