For any reason, maybe you need to view two windows at same time. Basically you can do it manually, just minimize first windows and then re-size it manually to best view and move it to left, next you need to minimize second windows and re-size manually to find best size and move it to right.
Windows 7/8 has a feature for it which Windows 7/8 just split the screen so you can view two windows with fastest way.
Here is step by step how to split screen on Windows 7/8:
1. Open first window.
2. Press [start] + [left arrow] and it will re-size your windows and move it to left.
3. Open second window.
4. Press [start] + [right arrow] and it will re-size your windows and move it to right.
5. You will have split screen on Windows 7/8.
This feature will make you easily to exchange active windows with just your mouse cursor. If you want to view other windows, just do above steps again but you can view two windows only. I think this feature will useful for any jobs such explore file or compare two files and many more.
I hope this tips will make you more comfortable with your computer.