Monitor Question...

I just recently purchase the dell 24"inch moniter and when I hook it up the picture does not come on .I have the dell xps gen 4 and the graphic card is a Geforce 6800. I tryed to goto the Geforce option screen,but how do you select the resolution of 1920x1200 and make it work with my moniter? Do I need to get a new video card, I already updated my drivers and I don't know what to do, there is nothing wrong with moniter because I tryed it on my friends dell and it works fine. Before I bought the 24inch I had the 19inch that came with the computer and the computer work fine .
Does anyone knows how to selcet the resolution can you e-mail my at darrelljackson@cox.net thankyou.

Right click on the desktop, click on Properties in this next box you see, click on Setting on top on the next box, which is Display Properties section, than slide the monitor resolution to the right.  Click apply, the screen will go blank for a few seconds, than another box will appear in the upper left side of the screen.  This will now ask you if you want to keep the new settings.  Click yes, and do it soon, or the old resolution will come back on.