How to set up multiple monitors on one computer
Why you need to know:
You may want to set up multiple monitors for more than one reason. One could be to run multiple programs on the computer without the displays interfering, for increased productivity. Maybe you would also like to have a wider display for image editing, watching videos, etc. Whatever the reason, it can be done in five simple steps, once the computer is compatible (the monitors do not even need to be of the same specifications).
What you will need:
Two or more monitors (start with two)
Two 'video out' connections (VGA, HDMI or DVI)
How to get it done:
Depending on the system unit or processor, the set-up could be as easy as using the correct wires to connect the monitors to the computer. Nonetheless, if your graphics card supports having more than one monitor connected, it will have more than one port for the video out connections. Remember, you can always purchase a compatible graphics card, or adapters for the wires to interchange from VGA to HDMI or DVI, vice versa.
Uninstall the current graphics card by going into Control Panel, Programs and Features, and then remove it. Once the new graphics card is installed, the computer should pick up the changes and you may update the drivers if required.
At present, the monitors may be connected, but only one will have a visible display. Right-click on the screen that is showing and select Personalize, Appearance, then Display Settings. The monitors should show in the settings with numbers on each and the options to mirror image (wallpaper) or stretch desktop across the two monitors. Note briefly, if the resolution of your screens is 1024 x 768, then the image you use for the wallpaper will have to be at least 2050x1000 to have an attractive (non-pixelated) desktop background.
The above instructions should apply to most operating systems. Follow through by purchasing adapters for the 'video out' cables for Mac computers and adjusting the settings in System Preferences on Mac OS.
http://www.pcworld.com/article/223014/make_multiple_monitors_work_for_you.html?%23tk.out_mod?=obnetwork or http://www.youtube.com/watch?v=JtzAQ1hao7U