actually it wud be not much improvement in performance. the only difference in 768mb would be good gaming on high resolution and high AA. i turn on 8X aa & 8xAF on and doesnt affect performance. you will get more frame buffers out of the more video memory. also its DDR3 RAM and not DDR2 so it wont be a load 192-bit interface plays good role and it has 96 unified shaders (more than 9600GT which has 64) and 9600GT got 256-bit mem interface so this card is as par or better performance as compared with 9600GT