O compiz é a versão 0.5.5, a minha placa de video é uma nVidia 7600GS, o xorg está correctamente configurado, mas aqui vai ele.
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 1.0 (buildmeister@builder3) Thu Oct 4 10:34:46 PDT 2007
# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig: version 1.0 (buildmeister@builder3) Thu Oct 4 10:33:51 PDT 2007
# /etc/X11/xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the xorg.conf(5) manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
# sudo dpkg-reconfigure -phigh xserver-xorg
Section "ServerLayout"
Identifier "Default Layout"
Screen 0 "Screen0" 0 0
InputDevice "Generic Keyboard"
InputDevice "Configured Mouse"
InputDevice "stylus" "SendCoreEvents"
InputDevice "cursor" "SendCoreEvents"
InputDevice "eraser" "SendCoreEvents"
EndSection
Section "Files"
# path to defoma fonts
FontPath "/usr/share/fonts/X11/misc"
FontPath "/usr/share/fonts/X11/cyrillic"
FontPath "/usr/share/fonts/X11/100dpi/:unscaled"
FontPath "/usr/share/fonts/X11/75dpi/:unscaled"
FontPath "/usr/share/fonts/X11/Type1"
FontPath "/usr/share/fonts/X11/100dpi"
FontPath "/usr/share/fonts/X11/75dpi"
FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection
Section "Module"
Load "i2c"
Load "bitmap"
Load "ddc"
Load "extmod"
Load "freetype"
Load "glx"
Load "int10"
Load "vbe"
EndSection
Section "ServerFlags"
Option "Xinerama" "0"
EndSection
Section "InputDevice"
Identifier "Generic Keyboard"
Driver "kbd"
Option "CoreKeyboard"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "pt"
EndSection
Section "InputDevice"
Identifier "Configured Mouse"
Driver "mouse"
Option "CorePointer"
Option "Device" "/dev/input/mice"
Option "Protocol" "ImPS/2"
Option "ZAxisMapping" "4 5"
Option "Emulate3Buttons" "true"
EndSection
Section "InputDevice"
Identifier "stylus"
Driver "wacom"
Option "Device" "/dev/input/wacom"
Option "Type" "stylus"
EndSection
Section "InputDevice"
Identifier "eraser"
Driver "wacom"
Option "Device" "/dev/input/wacom"
Option "Type" "eraser"
Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection
Section "InputDevice"
Identifier "cursor"
Driver "wacom"
Option "Device" "/dev/input/wacom"
Option "Type" "cursor"
Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection
Section "Monitor"
Identifier "L1730S"
HorizSync 30.0 - 70.0
Option "DPMS"
EndSection
Section "Monitor"
Identifier "Monitor0"
VendorName "Unknown"
ModelName "LG L1730S"
HorizSync 30.0 - 83.0
VertRefresh 56.0 - 75.0
EndSection
Section "Device"
Identifier "nVidia Corporation GeForce 7600 GS"
Driver "nvidia"
EndSection
Section "Device"
Identifier "Videocard0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce 7600 GS"
EndSection
Section "Screen"
Identifier "Default Screen"
Device "nVidia Corporation GeForce 7600 GS"
Monitor "L1730S"
DefaultDepth 24
SubSection "Display"
Depth 1
Modes "1280x1024" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 4
Modes "1280x1024" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 8
Modes "1280x1024" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 15
Modes "1280x1024" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1280x1024" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1280x1024" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
EndSection
Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
Option "TwinView" "0"
Option "metamodes" "1280x1024 +0+0; 800x600 +0+0; 640x480 +0+0"
EndSection
E comando que uso é o comando indicado na primeira mensagem