I suppose you're a developer, then?
Man, Firefox looks like crap no matter what you do. Why can't they at least try to make it look aqua-ish?
sorry, u will have to wait for firefox 3.0 late this year.
but
Nobody prevent you from downloading 3.0 Alpha with cocoa and aqua widgets here: http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-trunk/ (its more stable than safari 3 beta on windows