so if i get a comp as follows
intel core i7 960 3.2 ghz quad core intel x58 chipset overclocked to 3.9 ghz
6gb ddr3 2000mhz gtx-8 mem
750watt power supply
1x nvidia geforrce gtx 460 1gb video card
blah blah blah rest of system
will adding another vid card to go sli mode improve performance significantly?
will it be the difference in running in all high options as opposed to medium or low?
should i spend that extra 300 dollars?
and if 1 card is enough, is a gtx470 any better than the 460? they are basically the same
GTX 460s are very similar to the 470 in performance, but the 470 also run hotter and require more power. Both overclock nicely. I personally would rather get a 460.
I would say you could save yourself some money by going with the i7 930, the performance gains will not be worth the extra $300 spent on that processor. Maybe 1-2FPS and 300 on the benchmark.
Lastly, it is hard to say exactly how well this game will utilize SLI, as of now it doesn't seem like there is a lot of support, but with updated drivers and the final release you could see anywhere from 30-90% increase in performance (once again this is up to how well the game is coded for SLI and how well the SLI drivers work with the game).
What I would suggest is going an i7 930, gtx 460 and then a year down the road if people are getting good results with SLI, go purchase a second card (hopefully cheaper by that time as well).
Good luck with ur build!!