Here is how to do the snap function in Windows 7:
1. Click and hold on a title bar of one window.
2. While holding, drag your cursor to either the left or right edge of the screen.
3. Release the mouse button.
4. Click and hold a title bar of another window.
5. If the last window was docked to the right side of the screen, while holding, drag your cursor to the left edge of the screen. If the last window was docked to the left side of the screen, while holding, drag your cursor to the right edge of the screen.
6. Release the mouse button.
There you go! I hope I helped. ☺
For more features like this, watch this video: http://www.youtube.com/watch?v=DFiD9wh1HIY
☺