The thing with the CPU is, its speed is really important if you want to run with shadows and projectors on. The downside is SL does not take advantage of all those cores. An i5 is going to run SL just as well as an i7, but i7's come in slightly faster versions.
I put together a similar system as Ramen, an i5 2500. 8GB of memory and a sata III ssd. It ran fantastic until I tried running multiple instances of Firestorm. I put in another 8GB of memory and the problem was solved.