I got a reply to this via a member of the local MUG. Sounds like a good solution which I will try tonight.
Rick
If I understand what you are asking, instead of connecting to the old AirPort wirelessly, I suggest you wire the two AirPorts together. The old one connects to the internet via dial-up, but has it's wireless network turned off. Connect the two with an ethernet cable and use the new one for everything: printer, backup drive, and internet (via the old AirPort). This will take some special configuration on both AirPorts, but should work nicely. This will mean you won't have to switch wireless networks to change between connecting to the internet or connecting to your printer and backup drive.