500$GPU upgrade

I am in the market for a new GPU or GPUs around the 500$ price range.

I was thinking:

1) GTX 580
2) 2 GTX 470s oc editions
3) 2 Radeon 6870s

Or any other suggestions? I want something that I wont need to change for 2 years min which is why I'm leaning towards the 6870 or 470 route because in 2 years they will be obsoulte but I heard the 580 was f-ing awesome

580 is good, I would however wait two more weeks for the 6970 to arrive (dec. 13). Currently the speculation is geared towards it being a bit faster or on par with the 580, but nothing is sure, yet. Prices of the other cards are likely to drop when they are released.

Sli 470s or CF 6870s, but wait for a couple weeks for the price drops.