What is the best way to replace a 250 GB drive in my iMac (24" white)? I mean, I want to keep everything that is on it, so that I do not have to reinstall anything or lose anything. How do I, elegantly, transfer the data from one drive to another (bigger), including the OS (10.6.8.), without much risk and disruption? I do have another 250 GB back-up drive, using SuperDuper, btw.