dpkg -l | grep xserver-xorg-video
ii  xserver-xorg-video-ati                 1:6.14.99~git20110811.g93fc084-0ubuntu1 X.Org X server -- AMD/ATI display driver wrapper
ii  xserver-xorg-video-cirrus              1:1.3.2-2ubuntu7                        X.Org X server -- Cirrus display driver
ii  xserver-xorg-video-fbdev               1:0.4.2-3ubuntu6                        X.Org X server -- fbdev display driver
ii  xserver-xorg-video-mach64              6.9.0-1                                 X.Org X server -- ATI Mach64 display driver
ii  xserver-xorg-video-mga                 1:1.4.13.dfsg-3build1                   X.Org X server -- MGA display driver
ii  xserver-xorg-video-neomagic            1:1.2.5-2                               X.Org X server -- Neomagic display driver
ii  xserver-xorg-video-nouveau             1:0.0.16+git20110411+8378443-1          X.Org X server -- Nouveau display driver (experimental)
ii  xserver-xorg-video-openchrome          1:0.2.904+svn920-1                      X.Org X server -- VIA display driver
ii  xserver-xorg-video-qxl                 0.0.14-1                                X.Org X server -- QXL display driver
ii  xserver-xorg-video-r128                6.8.1-5                                 X.Org X server -- ATI r128 display driver
ii  xserver-xorg-video-radeon              1:6.14.99~git20110811.g93fc084-0ubuntu1 X.Org X server -- AMD/ATI Radeon display driver
ii  xserver-xorg-video-s3                  1:0.6.3-4                               X.Org X server -- legacy S3 display driver
ii  xserver-xorg-video-savage              1:2.3.2-3ubuntu2                        X.Org X server -- Savage display driver
ii  xserver-xorg-video-siliconmotion       1:1.7.5-1                               X.Org X server -- SiliconMotion display driver
ii  xserver-xorg-video-sis                 1:0.10.3-3                              X.Org X server -- SiS display driver
ii  xserver-xorg-video-sisusb              1:0.9.4-2                               X.Org X server -- SiS USB display driver
ii  xserver-xorg-video-tdfx                1:1.4.3-4                               X.Org X server -- tdfx display driver
ii  xserver-xorg-video-trident             1:1.3.4-2                               X.Org X server -- Trident display driver
ii  xserver-xorg-video-vesa                1:2.3.0-7                               X.Org X server -- VESA display driver
ii  xserver-xorg-video-vmware              1:11.0.3-2                              X.Org X server -- VMware display driver