The 13" one is a bit unusual: it shipped with a 160 GB HD which I thought a bit odd because the while MacBook available at the same time had 250 GB. And a higher-spec processor, too. That 13" used to be mine: I upgraded it to 4 GB of RAM and a 320 GB 7200 rpm HDD. That made its performance quite snappy in its day. Now it's used to keep track of a bunch of library books.