I received advice : to consider the AMD 6870 in preference to my choice of Intel 460 (*2Gb). I have read the reviews and a debating site. It seems that AMD is experiencing some difficulties with stability and the card is new and unknown, plus there is not a lot of difference in the performance(s). I conclude that it is better to stay with the tested and known quantity (Intel 460).
There seems a large opinion that overclocking is more effective with the 460 (I may never get around to learning to overclock and cyber-power is not offering any choices with respect to the 460 (2 Gb) card.
STILL, I conclude on balance, the choice is the 460 (2Gb)
As for the Radeon HD 6850 however, things are much more lopsided in AMD’s favor. It’s give and take depending on the benchmark, but ultimately it’s just as fast as the GTX 460 1GB on average, even though it’s officially $20 cheaper. And at the same time it draws less power and produces less noise than the GTX 460 1GB. In fact unless the GTX 460 1GB was cheaper than the 6850, we really can’t come up with a reason to buy it.