I am trying to decide between the new 2.4 GHz and the 2.6 GHz imacs. There is about $275 difference between them and a few differences. The difference I know nothing about is graphics cards. I would like to know how big a difference between an ATI Radeon HD 2400 XT with 128MB GDDR3 memory and an ATI Radeon HD 2600 HD with 256MB GDDR3 memory. I do not game, I will only use for personal photo editing and home videos. Is it worth the price premium for me? Thank you for your help.