here is an xorg.conf snippet from my gentoo machine
video card: nvidia geforce 8600 ts
monitor: sony gdm-fw900
this machine has the nvidia.com drivers installed
snippet:

Section "Device"
    Identifier     "nvidia geforce"
    Driver         "nvidia"
EndSection

Section "Screen"
    Identifier     "Screen 1"
    Device         "nvidia geforce"
    Monitor        "sony gdmfw900"
    DefaultDepth    24
    SubSection     "Display"
        Viewport    0 0
        Depth       16
        Modes      "1920x1200"
    EndSubSection
    SubSection     "Display"
        Viewport    0 0
        Depth       24
        Modes      "1920x1200"
    EndSubSection
EndSection

here is an xorg.conf snippet from my kubuntu 7.04 machine
video card: ati radeon 9600
monitor: sgi 1600sw
snippet:

Section "Device"
        Identifier      "ATI Technologies, Inc. RV350 AP [Radeon 9600]"
        BusID           "PCI:1:0:0"
        Driver "radeon"
        Option "DRI" "true"
        Option "AGPMode" "4"
        Option "AGPFastWrite" "true"
        Option "EnablePageFlip" "true"
        Option "backingstore" "true"
        Option "AllowGLXWithComposite" "true"
        Option "RenderAccel" "true"
        Option "XAANoOffscreenPixmaps" "true"
        Option "AGPSize" "32"
        Option "AccelMethode" "XAA"
        Option "SubPixelOrder" "NONE"
        Option "DynamicClocks" "true"
        Option "bioshotkeys" "true"
EndSection

Section "Monitor"
        Identifier      "SGI 1600SW"
        Option          "DPMS"
EndSection

Section "Screen"
        Identifier      "Default Screen"
        Device          "ATI Technologies, Inc. RV350 AP [Radeon 9600]"
        Monitor         "SGI 1600SW"
        DefaultDepth    24
        SubSection "Display"
                Depth           16
                Modes           "1600x1024"
        EndSubSection
        SubSection "Display"
                Depth           24
                Modes           "1600x1024"
        EndSubSection
EndSection