You think Aero is cool? Check Compiz Fusion out:

Video 1
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I can say that it is atleast 100 times better than Windows Aero.
I personally use Ubuntu 7.10 with Compiz, and works like a charm. When I enabled all possible Compiz plug-ins, the total memory usage of Ubuntu was just over 420MB, with Firefox on..

By the way, you CAN get the Aero look on Linux.. With Blur and everything: Random screenshot with the Aero look

Compiz Fusion might be faster, but Vista looks much cooler, than Linux default skins... And when you move the windows around in Fusion, they wiggle around to fast  

You can customize the speed of the wiggiling..

thats good