Dualhead on Linux? simple

If you think getting dual head display in Linux is kind of pain--you are mistaken, Xrandr has all the thing to get done, as simple as your igfxtray in your Windows boxes.

It's pretty simple, first check wheter the secondary display is activated. My laptop is Acer 4720z and my LCD screen is Acer AL1716WM.

$xrandr
Screen 0: minimum 320 x 200, current 2560 x 800, maximum 4096 x 4096
VGA connected 1280x800+1280+0 (normal left inverted right x axis y axis) 367mm x 229mm
1440x900 59.9 + 75.0 59.9
1280x800 74.9*
1152x864 75.0
1280x720 60.0
1024x768 75.0 70.1 60.0
832x624 74.6
800x600 72.2 75.0 60.3 56.2
640x480 75.0 72.8 66.7 59.9
720x400 70.1
LVDS connected 1280x800+0+0 (normal left inverted right x axis y axis) 303mm x 190mm
1280x800 59.9*+
1024x768 60.0
800x600 60.3
640x480 59.9
TV disconnected (normal left inverted right x axis y axis)

The VGA part is my monitor, and the LVDS is the laptop's display.

Then invoke the magic wand!
$xrandr --output LVDS --auto --left-of VGA

Whalla! You get the double head.