I Candy

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Beryl, a new fork of Compiz, is an extremely flashy window manager that runs on X.Org 7.1, which is the window server with AIGLX that's in Edgy.

Firstly, install the new beta NVIDIA graphics card drivers (note the requirements):

ctrl+alt+F1
sudo /etc/init.d/gdm stop
sudo ./NVIDIA_whatever.run
sudo /etc/init.d/gdm start
and run nvidia-xconfig --composite --add-argb-glx-visuals to modify /etc/X11/xorg.conf.

Then just add deb http://xgl.compiz.info/ edgy main-edgy main-edgy-amd64 as a source and apt-get install beryl.

More useful information here, maybe