Both cards are fairly evenly matched, but, the 6950 is the better bargain, priced normally about $100 less than the GTX570...
This is unfortunately incorrect. The 570 beats the 6950 in MOST situations, except when a game is optimized for AMD, in which case the 6950 will slightly surpass the 570. However, unless you are playing at resolutions higher than 1980x1650, the extra horsepower of the 570 is reaelly unnecesary.
The 6950 offers the best performance per dollar of any card out now and will easily trumph just about any game out there at 1080p except the most ridiculous.