My financee thinks I'm crazy. I already have a 2 month old intel 24 inch iMac with 4GB RAM that I barely used because I am never home. I travel a lot but my 17 inch gateway intel core 2 (T7200) was just too heavy to log in an out of airport 2 times a week so I gave her a practically new laptop. Anyways I brought a 2.2 gz Macbook yesterday; 5 pounds is light enough for me and I couldn't justify the Macbook Air's price tage. I haven't even booted up the computer. I already upgraded the RAM. Now I want to go to the store and buy a 320GB hard drive to replace the stock 120GB hard drive. So is it recommended prior to booting up the macbook to put a new hard drive in? Do I actually need to boot the laptop up....and than shut it down before I replace it? Last question is can I use the reinstall discs that came with the Macbook and just reload the OS and the default programs with my new unformated hard drive?