In older versions of Microsoft Windows it was never so easy to use external projector with your laptop because almost every laptop comes preloaded with some different set of display utilities, and every laptop has a different function key combination to enable output for a projector. The upcoming Window 7 has simplified the display switching issues marginally.
Note: This tip is mostly targeted towards those people who are switching to Windows 7 from Windows XP.
In order to switch display to projector, you will need to open Projector Display menu, Use any one of the following methods for this:
1. Press Win+P hotkey
2. Go to Start, type DisplaySwitch.exe and press Enter.
Both of the above will launch Projector Display Switch menu in Windows 7 as shown in following screenshot.
Now, choose the option you want to use, you can use Computer only (Show Desktop only on Computer), Duplicate (Duplicate Desktop on Projector), Extend (Extend Desktop to Projector), and Projector Only to Show Desktop only on projector. Enjoy!