Something more since you are preparing your order, take a look at my other post here
http://forum.1cpublishing.eu/showthr...t=23302&page=2
And, since you mentioned 2 x GTX570 which is exactly the setup I have, my advice today:
I personally would buy two 580GTX 3GbVRAM if I would go to the shop today so, unless if you want to play very high resolution (3072x and higher) you should to buy a single GTX580 3Gb VRAM GPU.
Should cost the same or be cheaper than 2 x 570GTX
Wait for the game to support 3Renders (3 monitors), by then the prices of GTX580 will have dropped and you can buy your second GTX580 when you will really need it.
I say this because the 1380Mb VRAM of the GTX570 is always at the limit at the resolution I play (3072x1024) so I will always recommend more than 1380Mb VRAM (you can see screenshots of the 570GTX VRAM usage in my pictures on the "SLI Working" thread).
Still, the 580GTX is a medium term solution so you will need to buy a new card in a year or two.
My 2cts...
~S~