I made some changes in the original Orange theme... and now it's works in Firefox 2.0. Al least, in a Windows PC.
If you find any bug please report it.
Install the Orange theme (Firefox 2.0)

Now you have two options:
-The Orange Theme (This is the original Orange theme, but... compatible with Firefox 1.5!!!).
-The Unofficial Orange Theme (compatible with Firefox 1.5). It introduces white tabs, orange letters in the tabs and a orange background in the tabbar.

Install the Orange theme
Install the Unofficial Orange theme

Ok. I make some fixes.
I removed "that strange dynamic link button in the address bar".
Now the theme looks better.
Install Orange for firefox 1.5
Thanks LeMarquis.

Drag and drop the jar file into the theme window. Click on OK when Firefox asks you if you want to install the theme. Restart firefox.
Easy, easy :)

This is a unofficial update of the Orange Theme for Firefox (by Maple.nu). You can use it meanwhile you wait the official update.
The theme have two little changes (you can see a preview in the picture).
Get the updated theme