New DELL screen

Hi, i just bought a new dell screen for my emac. it works perfectly (besides streaching the picture slightly...) but the emac screen is still on. is there a way of switching it off without turning the dell screen off

I don't believe there is a way to do this. I would just set them to spanning and enjoy the extra screen real estate. There is a piece of software that I can not remember i thinks its called something like "screen span doctor" which will allow the dell screen to be added to your emac screen so you will actually be gaining alot more from the purchase of the screen.