Firefox
The little browser that could is gaining momentum. The Mozilla Organization did a public preview release back in September, and apparently about eight million people have downloaded it since then. Today Mozilla released the final version of Firefox 1.0.
Free download; runs on Windows, Linux, and Mac OS X; smaller and faster and better-looking than Netscape Navigator, sleeker and less buggy and more advanced than IE. Arik Hesseldahl of Forbes wrote, in a commentary piece about the preview release: "[O]verall I like it much better than any other browser I've used. . . . Firefox is better than Explorer by leaps and bounds."
I still use Safari for my regular browsing. But I use Firefox now and then in various contexts and on various machines, and I like it better than any of the other browsers (other than Safari) that I've used. Go give it a try!