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woops, my bad. I was in a hurry. I had a crappy connection and i wanted to make sure it got out.
 
Sounds like the setup of your monitor, your hardware, and the limitations of the XBox 360 all work out really well in your case. The monitor has one DVI-D and one VGA, right? The MBP can use the DVI-D; the XBox cannot, but it can use the VGA. So you can have them both hooked up at once. :)
 
There's a "source" button on the LCD to switch between the two inputs.
 
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