View source for Xorg.conf

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "Quadro 2000M"
    Option         "RenderAccel"       "true"
    Option         "AddARGBGLXVisuals" "true"
    Option         "HWCursor"          "yes"
    Option         "CursorShadow"      "yes"
    Option         "RegistryDwords"    "EnableBrightnessControl=1"
EndSection


The ''Option         "RegistryDwords"    "EnableBrightnessControl=1"'' line allows you to change the brightness of the notebook's LCD via the Fn-HOME and Fn-END key combinations.


Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "TwinView"                  "1"
    Option         "DynamicTwinView"           "True"
    Option         "TwinViewXineramaInfoOrder" "DFP-1"
    Option         "MetaModes" "DFP-1: 1920x1200_60 +0+0, DFP-0: NULL, CRT: NULL; DFP-0: 1920x1080_60 +0+0, DFP-1: NULL, CRT: NULL;"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection


Here I set up the 2 MetaModes:
* notebook LCD off, external LCD on, VGA off
* notebook LCD on, external LCD off, VGA off


By setting CRT-0: NULL, you can save some battery by turning off the VGA port.