Take a look at this video:
http://www.youtube.com/watch?v=xC5uEe5OzNQ
It's a comparison between the new Windows Vista and Linux's Beryl. Hummm ... I need not say who the winner is.
Winfinit's XGL video looks just like Beryl to me.
As to your original question about desktop environments: You can create your own environment in Linux! There are multiple desktops (KDE, Gnome, XFCE, etc.) You can add things like Beryl and different window managers to spiffy it up and make your friends jealous!