scroggs,
I think you mentioned the problem:
both boxes use the same IP address
You need to change the IP Address on one of the two Routers. The Router in the Modem needs to be completely disabled and let the Linksys Router do all the PPPoE, (which you have done), and it should all work.
As for the issue with the WiFi Bridge that seacue was asking about, Microsoft has this to say about it:
Bridge May Not Work With a Non-Promiscuous Mode Network Adapter
This problem occurs because some NICs do not automatically enter into Promiscuous mode to create a successful network bridge.
Take Care,
Richard