Well, I'm on a white 2.4Ghz MacBook, and I'm currently running Leopard 10.5.7 and, i'm gonna upgrade to Snow Leopard first thing this friday. i have a couple questions, since this will be my first OS upgrade (just got my first macbook less than a year ago) 1. I don't have any back-up to my files, no time-capsule, no external hard-drives. and my hard disk is only 20 Gb free of space (from a total of 120GB), and if I lose my files, i'll most probably kill myself first thing this saturday! So, should I be worried or should I trust the upgrade system, and all of my files are kept them same? i mean, i have a lot of files in just folders and not in actual apps like iphoto and itunes... and my itunes library is about 40gb and my iphoto library about 20gb.... so, what to do?! 2. are all the apps (apple and 3rd party) kept the same?? i have ilife 09 and iwork 09 (i installed each one of those from a friend that had a family pack of each, but he's out of the country). and i have so many 3rd party apps... are they gonna be deleted? are their settings gonna be changed?? I'm not willing to lose any of those! Long Story short, what exactly Snow Leopard will do to my macbook's files once its installed... and is it better to just buy an external HD? (im on a tight budget but i think i can handle it) if so, which one do u guyz advice me to get, (but i prefer 1Tb and more)... and will it be good just to copy/paste everything or just do a time-machine back up??