want a gaming and just hot system. Have 2 128GB SSD drives raided systems drive, 1.5TB data drive, getting a EVGA GTX470 (another later in SLI) Windows 7, 1000watt supply, water cooled , 7 fan tower case. Gigabyte or ASUS mobo.
I would go with an I7 930. The Phenom II X6 don't game any better than their X4 counterparts because the extra cores can't be used by the games, it may change in the future, but I7 has a clear performance advantage when there isn't a gpu bottleneck.
Since you are planning SLI, you are pretty much locked with the X58 setup as socket AM3 and LGA 1156 (except EVGA boards i think) feature only crossfire as the multi GPU connectivity option.. So it looks like i7 930 is the way to go..