how to get external monitor only

I'm running OSX 10.7.4.
I have a MacBook Pro attached to an external monitor.
Because of where the notebook is in the house, for some reason, I can't get wireless to work on the Mac unless the screen is open. Seriously.
But I don't really need the laptop screen "on" at all since at home, I use an external monitor. Old Apple Cinema Monitor. Is there a keyboard "toggle" to shut off the laptop monitor and keep the external monitor on.
Thx.
Frank