Off the top of my head, I'd probably say Intel quad, (for graphic design # of cores is priority over clockspeed), 8gb of ram if you can get away with it (will require 64 bit, make sure everything is compatible first). If 64 doesn't work for you because of drivers or program compatibility, ther'es no reason to get more than 4gb since it will only recognize about 3.7 including what's on the GPU. Get a single nvidia 9800 or ati 4800 series card.The 4800s come in nice and cheap. You might be able to get away with less though I'm not sure exactly how much graphic design relies on the GPU other than for large high res monitor support. I just know the memory and processor emphasis. Also, no idea how much DDR2 versus DDR3 ram impacts that type of application.
EDIT: The FireGL and Quaddro cards (ati and nvidia respectively), are what you might actually want to look for as those are the workstation cards. From past experience though, I will say, while each is best at its primary purpose, gaming cards work better for workstation applications than workstation cards work for gaming applications.
ASUS P5E, E8500, 2x2GB Corsair DDR2 1066
Visiontek HD 4870, Antec 900, Corsair 750w PSU
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