Here is my situation, I will be buying a MBP in January that will have a 200GB HDD in it. I already have bought an external HDD on Black Friday (250GB WD Passport) and I plan on putting some of my less important files on it. Mainly about 60GB+ of videos that are in iTunes so that my main HDD will run faster. I want to buy an external Time Machine HDD but do not no the size I should get or the brand. Size wise, I know 500GB minimum but was thinking 750-1000GB might be better. Brand wise, I am thinking Western Digital or Seagate. I curently have an iTunes Library of 75GB+ that will keep rising thanks to my Media Center computer. That is the bulk of my files but it will grow more and more. Now to the Time Machine question. Will Time Machine back up both my laptop HDD and my other 250GB Passport HDD automatically or would I need to partition whatever external I decide upon so that I can have Time Machine back up my Main HDD and have me manually update the back up of the other external HDD?