I plan to get a 13" 2.26ghz Macbook Pro, and I have a 20" external monitor with a 1680×1050 resolution. First thing, I've barely used OS X, let alone with an external monitor. How well does OS X handle it? Is it pretty simple, and can I set separate backgrounds for each display? Secondly, will the GPU handle it alright, or will it be sluggish when I hook up the external? I'll mostly be using the 20" to do Photoshop work, with occasional video editing (though I have other computers available to do rendering on.) Any input helps. I'm a Mac newb through and through.