I upgraded my mini to a 320 gig hard drive, and I'm selling it to buy a macbook pro. I'm going to swap the 250 with the 320. Will that just work or will I have to reload the OS? I've made a time machine back up. I've seen the option after you install OSX to retrieve data from a time machine back up. How well does that work. Are there any concerns I should have with loosing data in this process?