Here are some benchmarks done by Tom's Hardware:
http://www.tomshardware.com/charts/2...hmarks,60.html
They benchmark across a wide variety of applications and games, so it should give you a pretty good idea. This chart is a few months old, however.
Just looking at the Far Cry test, frames per second only go up by 5 moving from the i5 to the i7. Is that worth the extra money? It depends on who you are I guess.