I don't think ED is that particularly hardware needy. I built my PC for flight sims three years ago and this game ran flat out without a twitch on it. I updated my GPU from a GTX570 to a 770 as a mid-term update but if I was only playing ED I wouldn't have needed to. I would say with a quad core cpu, a half decent graphics card, and a couple of gigs of ram it is happy enough.
If you want to ramp up the settings the impression I get is that the game needs more GPU ram than anything else which is pretty common in flight sims too, it's all those textures loading up I think.