It’s time say good-bye to those vendor-specific utilities and keystrokes toggling between the laptop screen and projector. Windows 7 now has its own new Presentation Mode that can easily turn on your projector and laptop screen at the same time. Simply press:
Windows key + P
As a bonus, the new Mobility Center looks cool and provides additional presentation options and a lot more. Simply press:
Windows key + X
Clicking Connect display button opens Presentation Mode.
For more Windows Key shortcuts, see The Use of Keyboard Shortcuts with Windows Logo Key.