some questions concern graphic card

hi, pals!

i'm thinking about upgrad my powrbook to a macbook pro 15-inch

it seems that currently there're two kinds of graphic card gos wit them. ATI Mobility Radeon X1600 graphics with 128MB SDRAM while another is 256mb. and it's about 500 usd more expensive

so is the difference significant? well i dunt play any games at all, and i hardly involv 3d. what i use will be Aperture and iMovie at most.

which one do you guys suggest? thank you