See http://goo.gl/KCluC

<monitors version="1">
  <configuration>
      <clone>no</clone>
      <output name="VGA1">
      </output>
      <output name="LVDS1">
          <vendor>LPL</vendor>
          <product>0x0000</product>
          <serial>0x00000000</serial>
          <width>1280</width>
          <height>800</height>
          <rate>60</rate>
          <x>0</x>
          <y>0</y>
          <rotation>normal</rotation>
          <reflect_x>no</reflect_x>
          <reflect_y>no</reflect_y>
          <primary>yes</primary>
      </output>
      <output name="DVI1">
      </output>
  </configuration>
  <configuration>
      <clone>no</clone>
      <output name="VGA1">
          <vendor>DEL</vendor>
          <product>0x403b</product>
          <serial>0x41555353</serial>
      </output>
      <output name="LVDS1">
          <vendor>LPL</vendor>
          <product>0x0000</product>
          <serial>0x00000000</serial>
          <width>1280</width>
          <height>800</height>
          <rate>60</rate>
          <x>0</x>
          <y>0</y>
          <rotation>normal</rotation>
          <reflect_x>no</reflect_x>
          <reflect_y>no</reflect_y>
          <primary>yes</primary>
      </output>
      <output name="DVI1">
      </output>
  </configuration>
  <configuration>
      <clone>no</clone>
      <output name="LVDS1">
          <vendor>LPL</vendor>
          <product>0x0000</product>
          <serial>0x00000000</serial>
          <width>1280</width>
          <height>800</height>
          <rate>60</rate>
          <x>0</x>
          <y>0</y>
          <rotation>normal</rotation>
          <reflect_x>no</reflect_x>
          <reflect_y>no</reflect_y>
          <primary>yes</primary>
      </output>
      <output name="VGA1">
          <vendor>DEL</vendor>
          <product>0x403b</product>
          <serial>0x41555353</serial>
      </output>
      <output name="HDMI1">
      </output>
  </configuration>
</monitors>