Firefox 3.7 and 4.0 Windows Theme Mockups

Mozilla just released its new theme screenshots for Mozilla Firefox 3.7 and 4.0. Compared to the current version — I’m using Firefox 3.5.3 — I think the design is much better. I like it. But, it’s still a mockup and it’s still far(?) from finish.
These are the mockups of Firefox 3.7 for Windows Vista/7 and XP:
ff_37_vista
ff_37_xp
And, this is for Mozilla Firefox 4.0.
ff_40_vista
More screenshots are available at Mozilla Wiki (Firefox 3.7 and 4.0 theme mockups). About the interface design, I think Opera has a great visual design.