Yes, it really depends on the I7 model you are referring to, not to mention the purpose of your acquisition. For gaming your best choices are I5 2500k(if u condider O.C)/2400(non O.C). For gaming and work(video editing, 2D/3D graphics, photoshop etc...) I7 2600k.
The most important thing is what you are going to be doing with your computer. On a gaming system since very few games can take advantage for more than 4 threads the value of threads has very little value in gaming. That is why for games right now the Intel® Core™ i5-2500K is the best processor for performance and value.
Now if you are going to be doing something that is heavily multi-threaded like Adobe CS5 than the extra threads that you get from the 1st generation Intel Core i7 processor or the 2nd generation Intel Core i7 processors can help out performance a good bit. So the Intel Core i7-990x or the new Intel Core i7-3960X Extreme Editions are going to be the best for this environment.