Well the thread clearly states the 280 GTX for 260 $ US is a very good price, only thing you should be concerned about is whether you'll be able to find anymore for sli in the future since its getting phased out by the 285 GTX which stands at 350$ US.
Are you planning on changing your video card ofter?
also I would wait for the 4890 to come out, its around the corner, and it should push prices down.
Also if your going i7, I would buy everything all together, that way you save up some money for decent purchases, and prices can only go down, usually don't go up