It's often helpful to view two windows on a single screen. Windows "Snap" allows you to quickly resize (snap) a window to the left or right half of the active screen (can also be used to maximize or minimize a window). This is one of my most frequently used Windows 7 and Windows 8 shortcuts.
To use this feature simply drag a window until your mouse bumps the left or right edge of the screen (to maximize a window bump the top of the screen). To fully utilize this feature in a multi-monitor setup, you need to use the keyboard shortcuts. The keyboard shortcuts are explained below:
First ensure the window you want to move and resize is selected. Then, press the Windows key and the up arrow to maximize it, the windows key and the down arrow to minimize it, and the windows key with the right or left arrow to dock the window to the left or right side of the screen (resize it to take up half the screen). When using multiple monitors you can also shunt windows between screens by repeatedly pressing one of the arrow key while holding down the Windows key.
It may sound confusing at first, but give it a try, I think you'll quickly find how useful this shortcut can be.