Camino is a Mac-only browser from the same folks who do FireFox. Camino is, to me, leaner, faster, and more Mac-like in its interface than older versions of FF.
Cookie management is easier (for me) than in FF.
The best thing is that the latest version, 1.6.8, still works on 10.3.9 and would be better than any old FireFox version.
Camino is here:
http://www.caminobrowser.org
It's what our house full of Mac dudes and dudettes use when Safari doesn't render the page correctly. My wife uses Camino exclusively on her eMac.