dimming screen on my mac with external monitor

[Sossity]

I have read mixed things about use of an external monitor with a mac laptop,

I notice in sys preferences for monitors, that I can dim my laptop monitor all the way to black.

can i just do this & then just have my external monitor on & in use?

I dont really want to do any tricky sleeping computer, & would be nice to have the lid open, so I can press the power button to boot up my mac without having to open & close the lid each time.

 

[simsaladimbamba]

You can also use the F1 and F2 keys to change brightness, but even when the internal display is dark, it is still on.
Have you looked at this yet?

InsomniaX
or
InsomniaT (rebuild for SL) (fix for 2011 MPBs)
or
Caffeine
​