I have been learning a lot since I started using linux ubuntu:

• to install Dreamweaver with wine
• to connect a network preinter with avahi and cups
• and now I have finally managed to set up a "Dual screen" so I can be more productive

I found most of the information in the xorg xrandr wiki, it took me 1 hour but the actual set up is very simple:

1. plug the external monitor before you swich on yout laptop and change the resolution with the GUI
   
2. back up yr /etc/X11/xorg.conf and generate a fresh one with
   

   sudo dpkg-reconfigure -phigh xserver-xorg     

3. Run xrandr --output LVDS --auto --left-of VGA to see the size of the virtual screen you need, it will return an error message saying your current max size and the one you need
   
4. edit the /etc/X11/xorg.conf and add the magic line with virtual (don't use mine!)
   

Section "Screen"
Identifier "Default Screen"
Device "Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller"
Monitor "Acer AL2251W"
DefaultDepth 24
SubSection "Display"
Modes "1680x1680" "1680x1050" "1600x1200" "1440x1440" "1280x1024" "1152x864" "1024x768" "832x624" "800x600" "720x400" "640x480"
Virtual 2880 1200
EndSubSection
EndSection

log out, run xrandr --output LVDS --auto --left-of VGA
and that's it! You can also put the laptop screen on the right with the option --right-of

IMPORTANT, DO NOT USE :



It doesn't work! and will break your xorg.conf :-(