If you want to quickly setup dual monitors in Windows 7, you can do that by using the Windows 7 shortcut Windows key + P. For more instructions check out this guide after the break.
Setting Up Dual Monitors in Windows 7

Windows 7 has some neat little enhancements, one of them being how it lets you handle dual monitors. If you’re adding a second monitor to your Windows 7 home or office PC, which is a very good idea, it’s a breeze to configure.

There are actually two ways you can currently setup multiple monitors in Windows 7, either by using a keyboard shortcut or via the traditional system properties.

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click Internet Options

(1) Simply press the Windows key and P (Windows + P) to bring up a quick menu of options.

Pretty neat! You can pick to show only the computer, make the second monitor a duplicate of the first, extend the desktop to the second monitor or turn off the first monitor and activate the second.

 

(2) The second way is to right-click on the desktop and choose Screen resolution.

Click Delete All

(3) Now you’ll see the familiar 1 and 2 to distinguish which monitor is which. There are several options and from the dropdown Multiple Displays, you can select the same options that you get when you press Win + P.

type in MSCONFIG