Firstly - no offence, secondly I post this in order to not let the consumer be consumed by a fancy alt-tab switch feature in vista.

Now as far as 3D desktop´s go there is no competition:

http://www.youtube.com/watch?v=LFGJDgLslnU

This is a real 3D desktop as opposed to a Microsoft toy desktop. Also this runs on my machine and the total resource footprint is a third of that of microsofts vanilla vista installation with no other software loaded.