Remember that Crossfiring a second card doesn't add the memory of the second card (so if you have two cards with 2GB of VRAM, they will still have just 2GB). The performance is not doubled either (it's something like 75% more). Single cards usually produce less heat and consume less power. You should also know that nvidia cards can only be crossfired with the same model, but ATi cards can be crossfired with cards from the same series (for example, you can crossfire a 5770 and a 5750).
That card you linked seems fine, can't bother to check if there is something with better price/power ratio though
I would go for ATi though, because I don't like nvidia 
And you really don't need 12GB of RAM. Go for 8GB if you want, but buying 2x2GB is more than enough.
And seriously, if Rift takes more than 4GB of RAM, the game has a serious memory leak.
That card you linked seems fine, can't bother to check if there is something with better price/power ratio though
I would go for ATi though, because I don't like nvidia And you really don't need 12GB of RAM. Go for 8GB if you want, but buying 2x2GB is more than enough.
And seriously, if Rift takes more than 4GB of RAM, the game has a serious memory leak.
The biggest problem of the human race is that they cannot accept that there is nothing after death.
