Honesty, when you ask a question you have a basic idea or inkling of what you want to go with, you just need extra push or reassurance to go with your decision, ku-sama, what do u really wanna go with? Becuase tbh in my view you cant notice a huge difference, and your only gunna have the card for roughly a year...heres my view, sell ur gs for 200, get the 7600gt for 100, save that other 100 and other cash u can save for dx10 cards for when they come out, so you will prolly have the 7600gt for not even 6 months.
And on top of that, if you found ur 6800gs as acceptable, the 7600gt will blow your mind, it really is a screamer in terms of performance to price.