I'm trying to build a bullet-proof backup system for my Macbook Pro on a modest budget and need some technical advice for choosing which hard drive to put in an external firewire enclosure. (OWC Mercury Elite-AL Quad-interface [Firewire 800/400, USB, eSata]) This is not the oft-repeated question of "Which HDD brand is the most reliable?" We should all know by now that all hard drives will fail sooner or later and it's the backup strategy that should keep you up at night. I've got the backup strategy nailed down (redundant copies of my laptop HDD and external HDD, plus off-site backup), and I've figured out I need a 750 GB or 1 TB SATA drive. The question is, which HDDs have performance and power-usage specs that make the best sense for an external backup drive that will only get written to for a nightly backup with SuperDuper plus occasional Time Machine writes in the background when I'm at my desk? Tom's Hardware Winter 2008 Hard Drive Guide gives a great technical look at today's top drives from WD, Seagate, Hitachi and Samsung. I don't know how to read these numbers (like average sequential read throughput or access time) to know what's relevant to my backup situation. Tom's Hardware also gives metrics on performance per watt, and another article highlights low-power-consumption as an important consideration for always-on externals. What metrics matter for backup-only drives? Should I go for so-called RAID class drives that are certified for 24/7 grinding? Should I go for one of these "green" drives that are low-performance but low power consumers? What's good for the long haul?