まぁ、Modelineとかも書く必要はないってことだ
俺のxorg.confはこれで全部。Linuxだけどさ

Section "Files"
ModulePath "/usr/lib/xorg/modules/extensions/nvidia"
ModulePath "/usr/lib/xorg/modules"
EndSection

Section "ServerFlags"
Option "AIGLX" "on"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "nvidia"
Option "AddARGBGLXVisuals" "True"
EndSection

Section "Extensions"
Option "Composite" "Enable"
EndSection