I decided to purchase a Matrox DualHead2Go Analog Edition to connect to the VGA output of my laptop. It's quite cheap (around 140€) and allows me to have two outputs instead of a single one, running either a dual 1024*768 pixels resolution or, as you can see on this screenshot, a dual 1280*1024 + the orginal 144*900 display of the laptop. Dont bother to scroll all the way right!

Here is the working /etc/X11/xorg.conf conf file that works on a Ubuntu Studio 8.04 laptop with a nVidia GeForce 7300. Beware if you use the nvidia-settings GUI application, since it removes the references to any non-US keyboard, you might get in trouble at login if you dont manually edit your /etc/X11/xorg.conf in the "InputDevice" section according to your own langauge! Once you logged in, your desktop shoudl work fine.

 # nvidia-settings: X configuration file generated by nvidia-settings
 # nvidia-settings:  version 1.0  (buildd@vernadsky)  Thu Jun  5 09:26:53 UTC 2008

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Files"
    RgbPath         "/usr/X11R6/lib/X11/rgb"
EndSection

Section "Module"
    Load           "dbe"
    Load           "extmod"
    Load           "type1"
    Load           "freetype"
    Load           "glx"
EndSection

Section "ServerFlags"
    Option         "Xinerama" "0"
EndSection

Section "InputDevice"

   # generated from default
   Identifier     "Mouse0"
   Driver         "mouse"
   Option         "Protocol" "auto"
   Option         "Device" "/dev/psaux"
   Option         "Emulate3Buttons" "no"
   Option         "ZAxisMapping" "4 5"

EndSection

Section "InputDevice"

   # generated from default
   Identifier     "Keyboard0"
   Driver         "kbd"
   Option         "XkbModel" "pc105"
   Option         "XkbLayout" "fr"
   Option         "XkbVariant"    "oss"
   Option         "XkbOptions"    "lv3:ralt_switch"

EndSection

Section "Monitor"

   # HorizSync source: edid, VertRefresh source: edid
   Identifier     "Monitor0"
   VendorName     "Unknown"
   ModelName      "Matrox"
   HorizSync       31.0 - 91.0
   VertRefresh     60.0 - 85.0
   Option         "DPMS"

EndSection

Section "Device"

   Identifier     "Videocard0"
   Driver         "nvidia"
   VendorName     "NVIDIA Corporation"
   BoardName      "Quadro NVS 110M"

EndSection

Section "Screen"

   Identifier     "Screen0"
   Device         "Videocard0"
   Monitor        "Monitor0"
   DefaultDepth    24
   Option         "TwinView" "1"
   Option         "TwinViewXineramaInfoOrder" "DFP-0"
   Option         "metamodes" "CRT: 2560x1024_60 +1440+0, DFP: 1440x900_60 +0+0"
   SubSection     "Display"
       Depth       24
   EndSubSection

EndSection