Okay so im getting a 15" MBP from the apple store. I want the 2.16 w/ 2GB ram, the guy said that they have one w/ 512 ram but they can install the 2GB's for the same price as the online will and it wont cost anymore than the online store...so, ive heard I should not buy memory from apple...is this one of those times? or will I be okay?