I made my homework, and I am quite tired of searching... I am still confused. My computer: My MacBook Pro Intel 2.33 Core 2 Duo 17" Display 160 GB Hard drive. I need a lot of space and a fast HD, so I saw excellent reviews on the 320 GB, 7200 RPM hard drive from Seagate, so excited, I was about to purchase it, but... First Diemma: I was looking to buy the Seagate Momentus 7200.3 Hard drive (300 GB, 7200 RPM) There is 2 versions: ST9320421AS and ST9320421ASG What is the difference and does it affect me? Second dilemma: I found this hard drive: Seagate Barracuda 7200.10 Hard Drive (500 GB, 7200 RPM) I found only one version: ST3500630A Would this HD fit and work with my Mac Book? Should I purchase this one instead of the 320 GB? Thank you!