I am looking to upgrade the performance of my computer for around $200, so I am wondering whether a processor or gpu upgrade would be better. I play games such as HL:2 and its source games, Battlefield 2, and FEAR. I also do work with Photoshop. I currently have an AMD 3700+ in an ASUS SLI mobo with 1GB Corsair XMS. My graphics card is a 6600GT 128mb with a 19in widescreen LCD at 1440x900. Whichever upgrade would be better, do you also have parts suggestions?