Which Latitude Laptop best for Photo Editing with High Res Monitor connected?

I want to get a Latitude laptop with a complete docking station that drives the Dell UltraSharp U2711 monitor with max native resolution (2,560x1,440). Because of the need to drive a high res monitor do I need a laptop with a special video card ... or ... would the additional high performance video card provide better performance for editing in Photshop. I would probably add the max memory to the laptop. Any other important additions that your recommend?

I would prefer the 14 inch laptops for portability. I will do my photo editing connected to the desktop monitor via the docking staition. I need the portability for business purposes. The Precision laptops are too expensive for me.

The entire matter is a bit confusing.because it's not clear to me what laptop video card will drive the monitor at native resolution. Also the monitor/laptop connection is done via the docking station. So does the docking station also need to be capable of supporting 2560x1440? I plan on getting the compete docking station ($200)

I love my 5 or 6 year old Dell Inspiron 600m with my dociking station. I pop it in and I get my laptop charged, all my connections to keyboard, mouse, backup hardrive,,etc. It's a great laptop. Are the neW Dell Laitutudes as good? Which one should I get?

Thanks,

- Simon