I'd recommend a 2.5" laptop drive even in the case of building your own homebrew enclosure. They are indeed more forgiving to the forces of inertia while running.
Then again, 1 gig compact flash cards are getting pretty cheap, too. No moving parts at all to be affected by bumps, potholes, ricers caught in the fenderwell, etc.
As for "how to hook it up" as per your original post, you're pretty much stuck going the inverter / standard PC power supply route unless you can either find for a reasonable price or design and build a nice 12 volt powered switching power supply that delivers +5, -5, +12, and -12 volts DC.