install Xgl in ubuntu

deb http://www.beerorkid.com/compiz/ dapper main
deb http://xgl.compiz.info/ dapper main

if it notic the there has no public key,use this:
gpg –keyserver subkeys.pgp.net –recv-keys 0×31a5f97fed8a569e
gpg –export –armor 0×31a5f97fed8a569e | sudo apt-key add -

apt-get install xserver-xgl compiz-gnome