I just purchased a WD passport External Harddrive. The plan is to pop it out and put it in my Macbook and place the internal drive in the enclosure. I have not installed it yet to my MacBook. I think there is a possibility that my 320 GB 5400 Harddrive has a 2MB cache as opposed to 8 MB cache. Which leads to the question: Is there much performance difference between the 2MB and 8MB drives when used in a MacBook?