I could really use the opinion of anyone that has used both of these computers. I dont need portability any more, so i just sold my MBA. The iMacs that i can most afford right now are mostly Core 2 Duos... But looking at the benchmarks, they seem quite a bit slower than my MBA. But in real world usage, would i really notice much difference? Would paying $750-$800 (to step up to a i5 Quad Core) be really beneficial versus $450 for the above spec'd machine?