iirc, 5970>6990 for mining anyway! 3200/3072 shaders respectively.
But the prices are still quite high for 6990 as compared to 5970 and we are looking at only a 10-20% increase in performance.
Yeah! That's what I'm saying. If it's for mining, 3-$400 for a 5970 is great. Even for gaming I'd just take the 5970, as cheap as it is. But, the 5970 is better than the 6990 for mining anyway, so it's a no-brainer.
The 7xxx series is still up in the air. No one knows what will happen with them. If they turn out running like a Fermi, those 5xxx cards are (still) going to be hot commodities.