I almost had it the other day, but I was tired and had to get the network back into a working state for Jenny.
Today, I tore the problem into two pieces. I turned the router into a bridge and then I verified that the bridge worked using my Mac and PPPoE. Worked. Great.
That problem greatly simplified, I then had to go in and wipe the wireless access point. Something in it was corrupt. I configured everything and whammo, didn't work.
After an interruption, I turned around to find that it had a conversation.
So YAY, all that is done. I turned off the Mindspring modem. If all goes well, I drop the Mindspring service next week.