Why not get the 920 and OC it? Save yourself $700 to spend elsewhere on the system? And as fast as technology moves these days it's pretty hard to 'future-proof'. 6 Core i7's are coming later this year. -> link <-

I'm sure 8 core home system processors are right around the corner as well. If you want to future proof, and seem to have all this money, I'd look at a dual 4 core Xeon system with 64GB [or more] memory...that should last you some time.