Hi Guys I decided to switch Mac from PC after years of windows hell! i got a white MB 2GHZ, 2 gig RAM (from DMS), and 60 gig HD,I am in love with this computer. my Question is with regard to upgrading my HD to 100 gig, 7200: 1- Do you recommend that? and How easy (changing the RAM was very easy for me) 2- What brand? and How much? 3-Do I need to format the new HD?and reinstall all my software?