using a projector as a second monitor w/laptop?

[tonypaladino]

Ok, so I have a digital projector, and I thought, why not use it as a second screen projected on the wall behind my desk?

I have it hooked up to the S-Video jack, but I cannot get the display to work as a second monitor, I seem to be able to only have it project whatever's on the screen, or the screen turns off and display is only through the projector.

Do I need to hook it up to the monitor jack for it to work as two monitors, or is there some sort of setting I can adjust.

Thanks
TONY