External monitor Help

I just bought a minidiplay->DVI connector
trying to connect my dell display to it.

how do I go about setting up the settings.

I used to have insomniaX.. but since i installed SL it doesnt work.. I am not srue if I need to use SL for external display.

How do I go about changing the settings on the mac for external dipslay?
and make sure it doesnt fall a sleep on me


thanks,
arpit

 

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