I want to backup my MacBook Pro to an external HD. Problem is I'm on a college student's budget (i.e., not much) so I need to keep the cost to a (reasonable) minimum. My MBP's internal HD is 200GB, with 90GB currently used, and I want to create 2 partitions, one for a bootable duplicate and one for a Time Machine backup. Will a 500GB external Hard Drive be sufficient? I assume I need to partition it into 200GB/300GB...but I'm not sure that 300GB (or however much less based on the formatted capacity) is enough for a satisfactory backup. Searching these forums and google led me to a number of threads in which it was recommended that one should buy a backup drive that's 2x or at the very least 1.5x the size of one's internal HD...and 300GB just barely meets that (and, again, it misses the mark when considering actual formatted capacity). Is there another option for the bootable duplicate or is that even necessary/useful? Or would it be ultimately useless unless I go for e.g. 640GB or 750GB? And, I also read that TM is effectively locked into an hourly/daily/weekly schedule. Will the process still work well if I e.g. connect my MBP every sunday night and just backup weekly? Thanks!