In my quest to skin everything I ran across this website that describes how to use some of the greatest Mac OS X Safari/Firefox skins on your Windows Firefox 3.x browser. It even provides a link to the Mozilla Adon site that lets you install them. I have done this for both the all time great GrApple Delicious and GrApple Yummy Mac OS X themes and they work GREAT. Check out the article called "A Better Mac OS X Leopard Theme for Firefox 3" [link]
and try the links for Delicious [link]
and Yummy [link]
GrApple themes on Windows Firefox. I have attached a screen shot. It actually works and they are great looking authentic Apple themes.