I'm about to pull the trigger on a new imac. I really want a 27 incher but I am worried that the C2D 3.06 is getting a bit old and wouldn't be as relevant in a year or two as the i5 or i7. I've read many threads on those two and understand them well. Will I see a big speed increase from a 2.0ghz C2D to a 3.06????