Sandy bridge functions really well with 1600Mhz Ram@1.5v. The low voltage RAM kit above is the better deal.
2133 RAM won't do you much good, unless you plan on OC'ing. You will, more than likely, have to give 2133Mhz a voltage bump.
Intel i7 2600K @4.2Ghz
16GB Corsair Vengeance Blue 1600Mhz RAM @1.5v
HAF X RC-942 black full sized tower
Corsair H80 Liquid Cooler
1x 240Gb OCZ Vertex 3 Sata 600
1x 1TB WD Caviar Black WDFAEX1002
LG SuperMulti Blue BH10LS30
Scythe Kaze Master Pro fan control KM03-BK
2x MSI n580GTX Lightning sli
Windows 7 Ultimate 64bit
Here's some info .... with the 2500k and not the 2600k, I gotta guess that gaming is the goal. FAst RAM is much more important with the 2600k as if ya sprung for HT, generally the apps that like HT benefit much more from fast RAM. But that doesn't mean there is no advantage for gaming......it' small, but generally the performance increase (3-5%) is bigger than the increase in system (2-4%) cost.
22.3 % (SLI) increase in minimum frame rates w/ C6 instead of C8 in Far Cry 2
18% (single card) / 5% (SLI) increase in minimum frame rates w/ C6 instead of C8 in Dawn of War
15% (single card) / 5% (SLI) increase in minimum frame rates w/ C6 instead of C8 in World in Conflict