Thanks for reading, folks! My old MBP died (logic board problems) so I got a SATA external enclosure for the HD. My problem: I don't know what to delete from the HD (since it has the full OS on it currently) such that anything I want to save from it will function correctly. For example, I want to keep my catalog for Lightroom in full working order. What do I do to make sure that happens? What about Pages? You get the point. I have transferred my entire user folder to another computer already. Is that it? What about applications? If I get rid of those, what will happen when I delete the Library? Will the programs still be functional? And question 2: How do I go about formatting the HD?