honestly I7 p50, if your building a gaming system. the i7-2600k. is a good one, but its gear toward the budget builder or someone looking for a nice all around CPU, that will do good for game`s and for videos off the net.

they are both close to each other, in the way they handle things, But i would have to say go for the i7-950.

i7 2600k would be faster.

I'm running a 2500k @ 4.3ghz on air. Any K sandy bridge will run 4ghz or higher on air. There is not much to gain from tri channel memory. Pretty much a night and day difference in speed when i moved from my q9300 to the i5 2500k.

If do plan on nehalem don't bother buying it wait for intels Ivy bridge since its the replacement. Also 1366 is pretty much dead since sandy bridge came out.

sandy bridge is a die shrinks and a tweaked version of Nehalem. you need to take the p serie i think to overclock the sandy bridge but you won't be able to use the on-die gpu whit the P serie . no oc for non K chips.
and IPC is just 3% higher on sandy bridge

Yea, a lot of people are now leaning towards the i7-2600K.