A buddy of mine and his girlfriend both have macbooks. His is a first gen Core Duo and her's is an early 08 blackbook. Her hard drive died, so he is "buying" her a new one, but what he really is doing is reformatting his (his is a newer Seagate, 160gb), installing OSX, and pulling it out and sending it to her (she's in Texas, he's at school up here). He then plans to use the new Seagate 320gb he just bought in his macbook. Is there any reason that an OSX install on the same hard drive wouldn't work in 2 different computers?