The 7600 is holding you back...
Yea, I miss typed it.He has a 7800. And yes its the 7800 holding ya back. Even tho my card is just a midrange 128bit card , my clock are still almost twice that of your 7800. Your systems set up for an 8800 I would go for it. The 8800 gt's are only 150 to 170$ . Start saving.
Also , ignore 3d mark , my computer only gets a 5000. But my computer plays my games perfectly , I'm very happy with the performance. And thats all that matters. Is that your pc plays your games at the speed you want.