I plan on OCing the sh#t out of the CPU but I just asked the question a specific way to get the answer I was looking for. I never said I planned on keeping it at stock speeds.
Just having a real hard time picking a GPU and deciding if I want to wait for ivy bridge or get the 2600k...
...so why bother asking how it will perform if you're never going to run it that way in the first place?
For what it's worth, there will be more processors coming out in the Sandy Bridge line yet in 2011. The extreme editions (LGA 2011, **** you Intel for changing motherboard specs so much) are slated for Q3-Q4 this year. The i3's are coming out in a few weeks as well, by the way. Ivy Bridge won't hit for another year or so and it'll just be a die shrink like Westermere, the 980x, was. At that point, if you're willing to wait a year for a new processor, you'll never upgrade. Once Ivy Bridge comes out, Haswell will be a new architecture coming out in another year, then Rockwell a year after, and so on. Moore's law will keep rolling on.
The 2600k is definitely an improvement over the 2500k. It's definitely a price jump as well, another 50% higher, but that's roughly what the performance jump is too. Ivy Bridge will still run on the same socket so you won't have to worry about buying a different motherboard in that scenario. And for what it's worth, the 2500k itself is a strong processor, overpowering one of the staples of the 1st gen top tier i7's, the 950.
tl;dr: Think of the 2500k v. the 2600k as the 950 v. the 980x, except now they're both cheaper and fairly priced instead of the better one costing a ******* extra.
Oh and that GPU will do fine, it's a balanced competitor for the similarly priced Radeon 6000's, boils down to more personal choice basically (driver support, SLI/crossfire, cooling, etc).