hey so I was thinking that since i have a 500gb external hard drive and would like to use it as a backup for my internal 160gb hard drive and that I should use time machine. well due to that my machine only has a 160gb internal HD I don't want to dedicate the entire 500gb's to time machine. so I was thinking of partitioning 165gb's for time machine and the rest in another partition to just use for whatever. now my problem is how would I go about doing this? and so that time machine always backs up to the 165gb partition. also that I could access both partitions easily. but first is this even possible? is it not recommended? and not a good idea? also if possible could I make two 165gb partitions and one with the remaining 170gb's and use both 165gb partitions as time machine back ups? that way I could back up two computers to one drive on separate partitions and also have 170 for whatever I need it for?