My friend is offering me a macbook pro for a cheap price because he is switching back to a PC. I currently own a 2.66 C2D macbook pro with 4Gb ram. His macbook pro is brand new last week 2.4 i5 with 4Gb ram. How much improvement from C2D to i5? Does it make sense for me to upgrade? I'm familiar with the graphic cards and such. Thank you!