Deep 7 is an impressive visual style hack for Windows 7 that completely customizes almost every aspect of the interface. It’s really worth a look.
You’ll need to make sure you’ve already hacked your visual styles, or at least installed UxStyle before you can install it. Hit the link for the full preview with close-up screenshots of some of the window elements.
Note: “hacking” your system implies that you should understand that there could be consequences to said hacking, including issues with your system.
dEEP 7 3.0 [deviantART]