So since my HDD is failing, i am going to upgrade my HDD from 160GB to 640GB which i hear is the max my macbook can take. As of now i am confused on which to buy. i was looking around Newegg and amazon, and found many. should i get this one: Amazon or any of these from Newegg do not really know what the differences are other than the prices. does all this matter: Cache: 16MB Average Seek Time: 8.9ms Features: Reduced power consumption - WD has reduced power consumption by up to 40 percent compared to standard desktop drives with the combination of WD's IntelliSeek, NoTouch, and IntelliPower technologies IntelliPower - A fine-tuned balance of spin speed, transfer rate and caching algorithms designed to deliver both significant power savings and solid... not sure what to look for, and what to avoid. what is SATA since it says 3.0GB. and lastly why is the western scorpio blue cost more if it seems to have the same specs as cheaper models there; it also tends to lack on RPM with only 5400. wouldn't that make it slower? or in this case it is better? i use photoshop a lot so im pretty sure more RPM is good. thanks.