Hi, I need your helps. I am a newbie to mac. I just bought MBP. I would like to upgrade hard drive to 320GB. I want to do by myself. 1. I would like to know in case I have to send MBP back to apple store. Would warranty will be cancelled according to I upgrade hard drive myself? Or if I change the it back to the original hard drive, it would be okay? 2. When I buy a new hard drive. What should I do with it? I have to install mac os first? Thank you for your helps.