The corrupted model name sounds almost like a bad cable. Can you get any other machines to recognize the drive correctly and format it (maybe using your external enclosure)?
Which hard drive did you test using the enclosure -- the 40GB or the 30GB one? You should test both with another computer to make sure it actually was the 40GB drive that was broken and not the cable or logic board.
To solve your power supply problem -- try to find (or make?) a USB cable that has 2 male plugs (to plug in to 2 USB slots), or buy/borrow a Firewire enclosure.