If you frequently hook up your laptop to a projector, or use an external monitor there’s a shortcut in Windows 7 that can be helpful.

1. On your keyboard, hold down the Windows key  and press P
2. A window like this will pop up:

• You can choose one of four screen modes:
• Computer only: This shows your desktop only on your computer screen.
• Duplicate: This shows your desktop on both your computer screen and a projector.
• Extend: This extends your desktop from your computer screen to a projector.
• Projector only: This shows your desktop only on a projector.