Smart Window or Snap, allows the user to view two windows side-by-side in Windows 7 without having to manually re-sizing either window. This is also useful if you don't want to use Alt-Tab between 2 windows. If you are running an earlier version of Windows such as Windows XP or Windows Vista see the Split and arrange open windows tip for suggestions.
Click and Drag on the top title bar of the first window so your mouse pointer hits either the left or right side of your screen. Let go of the window when you see the outline of the window re-size to ½ of the screen.
Then choose the other window you wish to view on the side of the first window. Click and Drag the 2nd window to the opposite side of the screen until the mouse pointer hits the side of the screen and resizes to the other ½ of the screen.