I've been on Firefox for about a month now. I couldn't be happier. I especially love the extensions. I suggest you try out Adblock, ForecastFox, FoxyTunes (if you like to listen to music as you surf) and IEview which is good when you encounter a page that is viewed better on IE (very rare but happens).

Other features I love are the search feature that lets you search amazon, google, etc. and you can add others if you want. I also like the download manager.