Display Projection.

Had enough of messing around with weird and wonderful OEM display driver utilities to get your notebook display onto an external projector? In that case, you’ll be pleased to know that projection is really quick and simple with Windows 7. Just hit Win+P, and you’ll be rewarded by the following pop-up window:











The Win+P Projector Settings window allows you to quickly switch display settings.
Use the arrow keys (or keep hitting Win+P) to switch to “clone”, “extend” or “external only” display settings. You can also access the application as displayswitch.exe.

If you want broader control over presentation settings, you can also press Win+X to open the Windows Mobility Center, which allows you to turn on a presentation “mode” that switches IM clients to do not disturb, disables screensavers, sets a neutral wallpaper etc. (Note that this feature is also available in Windows Vista.)

(from msdn blog)