tips on which 15" Macbook Pro to buy - recording and home

Hi,

I have a 5+ year old Macbook and have decided it is time to upgrade. I have used it for both for when I went back to school and home useage. I also do some recording on it - mostly live instruments (lots of drums), using Logic Pro 9 now (probably will upgrade that as well). I'd like to upgrade to a Macbook Pro, would like to have 15" (prefer the bigger screen over the 13").

My question, do I go for the more ram and storage of the 2,599, or will the 1,999 version be enough?

I will probably be using external storage anyway, so I amy not need that, however the faster processor and the extra ram seem to make sense.

thanks in advance for your help