To be candid I am not familiar with the video cards available from Dell. It is probably the brand of computer, excepting their overly expensive workstations series, I would least likely recommend for digital photography.

The video card business has been in flux in the last year or so with one of the better sources being bought out by AMD. However, from independent PC component dealers like Tiger Direct high performance ATI graphics cards remain available. However some models are optimized for gaming and provide no advantage to 2D photo image processing and running Photoshop. The other video processor with a good reputation is nVidia.