If your motherboard supports crossfire, go for the 6850 and add another later. The evga ftw edition of the 460 is a beast too. The 6850 consumes less power and has less heat, it's also cheaper.
Well, Im not bying a OC'd card. I have found two stock cards on a Norwegian site, to the exact same price, so I was wondering which one I should go for. And no, my motherboard only supports SLI.