This one is more of a specification question. I want to upgrade the HD in my Macbook from a 160GB HD to big 320 GB HD. I also need a portable HD. So I was considering buying an external drive, (like a Maxtor Onetouch) swapping the drives and running the 2.5" drive that came in the enclosure inside my Macbook. Is this a good idea? Are the drives that come in the portable enclosures worthy of being the primary drive in a Macbook?