This is pretty much an old stuff. If you want to customize Windows a lot more than what Microsoft offers out of the box, you can install 3rd part customization software. One of the most popular software is from http://www.stardock.com/ . It has a lot of things you can do with your Windows appearance. Like your Windows style, icons, animated background like Dream Scene, and a lot more.

 

ObjectDock is one of their software. I believe it has been quite awhile now; I just didn't care enough to try it.

On the surface, it looks like those Mac application launcher. It offers tons of customizations. For instance, take out all the quick launch icons. I use this as taskbar. I have been wanting this kind of taskbar after Vista comes out.

 

ObjectDock uses Vista to render real time thumbnails (if I am not mistaken). And whala, a taskbar based on thumbnails. In case of emergency, I added the toggle button to hide it.