I know most of you have been using this this feature but had to do more research for simple customization.
In my work location I had to arrange my additional Monitor on left side. By default, My Windows-7 Laptop assumes the Monitor is on right side and it is a struggle to move a program between both monitors. You may change the settings as follows to move Second monitor to any direction you need (You may configure it in to any side, corner, up and down).
How to change?
Control Panel -> Display -> Change Display Settings -> Drag one of the Monitor (1 or 2) positions. (Monitor 1 will be Laptop screen and 2 will be additional Monitor)
Refer to The HTG Guide to Adding an Extra Monitor to Your Laptop for initial configuration…