I LOVE it AS-IS!
Only one suggestion, I did not check in IE but in FF the css for the location of the tabs need to have it indented a bit more to the right, it is just slightly hanging over that rounded corner so perhaps if it has a margin or px offset add about 5 px or so.
Very nice, simple, colorful yet not toooooo colorful, simple icons and functional with the tabs up top....
4.5 out f 5