In my humble opinion, I wouldn't buy the 680GTX if I already had a 580GTX. There would be a performance boost, but would it be enough to justify the $500-$600 price tag? Just for another 20 fps? If you had a 9800GTX+ like me (please, don't be jealous), then obviously the 680GTX would be worth it. Of course, waiting for Nvidia to release better drivers down the road will help boost productivity making the 680GTX even better. But, it's up to you. Just my two cent's worth.