I was experiencing some problems with my dual screen setup on my Dell Precision M4500 notebook with Fedora 15. Now that I finally have it up and running, I thought I might share my configuration as well.

Update: You have to enable the rpmfusion repositories.

When using the 'free as in freedom' nouveau driver, I experienced a lot of system hangs. I guess this is due to Fedora bug 618143. So I installed the freedom hating NVidia driver as follows:

su -c "yum install akmod-nvidia xorg-x11-drv-nvidia"

I think I have to install akmod-nvidia instead of kmod-nvidia because F15 is still in beta, but I am not sure about that.

Update: The following doesn't apply anymore for recent versions of Fedora. If you have troubles with your display configuration, I recommend trying arandr. It allows saving your configuration as a shell script, which is cool.

The nvidia-settings tool seems very buggy, and I didn't manage to generate a xorg.conf file. Luckily I had an old file, which worked fine. I put the following in /etc/X11/xorg.conf:

Section "ServerLayout"
    Identifier     "Default Layout"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    Option         "Xinerama" "0"
EndSection

Section "InputDevice"
    # generated from data in "/etc/sysconfig/keyboard"
    Identifier     "Keyboard0"
    Driver         "kbd"
    Option         "XkbLayout" "us_intl"
    Option         "XkbModel" "pc105"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/input/mice"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "DELL 2009W"
    HorizSync       30.0 - 83.0
    VertRefresh     56.0 - 75.0
EndSection

Section "Device"
    Identifier     "Videocard0"
    Driver         "nvidia"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "Quadro FX 1800M"
EndSection

Section "Screen"
    Identifier     "Default Screen"
    Device         "Videocard0"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "TwinView" "1"
    Option         "metamodes" "CRT: nvidia-auto-select +0+0, DFP: nvidia-auto-select +1680+0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

(My external screen is placed at the left of my laptop. If your configuration is different, I guess you'l have to do some tweaking.)