MacBook Pro 13" or MacBook Pro 15"

Hi all,

i'm a PC user now and am going to convert to a Mac. Am currently considering the base model for the 13" and 15". (i've copied the specs at the end of the e-mail)

Usage:

i'm just a casual photographer and use mainly Lightroom to edit my photos (RAW files) and occassionally use CS to stitch panoramas.

Therefore, I would need advise whether the 6MB cache on the i5 (15" MBP) would make a lot of different compared the the 3MB cache on the Core 2 Duo (13" MBP).

Thank you all in advance for your advice!!!

13-inch: 2.66GHz
4GB Memory
250GB hard drive1
SD card slot
Built-in battery (10 hours)
NVIDIA GeForce 320M graphics
$1,199.00

15-inch: 2.4GHz
Intel Core i5
4GB Memory
320GB hard drive
SD card slot
Built-in battery (8-9 hour)
Intel HD Graphics
NVIDIA GeForce GT 330M with 256MB
$1,799.00