To me it does sound like a problem with the hard drives in the 475 and the Performa. It might be worth swapping the drives you're having problems with with known good ones and trying the install on them, if you have any good ones floating around. If the install goes well on the good drives that would theoretically rule out the rest of the hardware in the 475 and Performa, especially if the "bad" drives also don't work right in another computer.

Great job on the recap!!!