Uh, no, Photoshop doesn't use graphics memory last time I checked - it's all main memory. Photoshop isn't even a 64bit app either, yet.
Base system wise, you can get as small as you want. mITX boards are tiny but capable these days. Bindi is right on the HDD; one unit, as large capacity as possible. Look at the new Samsung 1 Tb unit. The graphic card is the only point of concession. The latest just-below-the-top Ati cards like the HD 3850 give slightly more bang for slightly less heat. You may have to mod the case to allow for adequate ventilation.
