Thanks, tacit.
This string has gotten somewhat confusing, and I'm not sure if I put in every step -- but let me summarize:
The firmware update 1.2 seemed to work. Once I completed that, I was able to begin the 9.1 installation okay. At least, it didn't tell me I needed to update something else first.
After about 15 seconds of humming along, it said, "A problem was found but has been repaired," and then it continued to hum along.
Finally, after about 30 seconds, it said there was a problem with the Installation Tome source and installation could not continue.
I went back to the Apple knowledge base, problems with "Installation tomes" and it said, first, try wiping the CD on the underside, with a clean dry cloth, from spindle toward the outer rim.
As soon as I turned it over, I saw little specks on it. I tried to wipe them off, but it wouldn't work at all. I wrote back to the guy whom I bought the CD from, and he is sending me another one. Hopefully, that one will work!
But I appreciate all of the advice & links here -- they have been very helpful, AS USUAL!