yikes i'm calling now to see if they can help me (Apple customer support) as I just ordered mine with the lowest 250gb HDD as I already have a 320gb drive i wanna throw in there, or even if I want to upgrade to a 500gb drive, newegg has a 7200rpm for 130, Apple wants an extra 135 to upgrade from 250
hopefully we get an answer soon so i can alter my order if need be