I wasn't able to find this by going through Proxim's "front door"--in spite of email xchange w/tech support...got it thanks to finding Derek K. Miller's fine site in Canada. Grab this driver while you still can! Here's the link:
http://www.proxim.com/support/all/orinoco/software/dl2002_orinoco_client_r72_macos.html

And here's Dereks' step-by-step instructions for getting old Mac laptops on a WiFi network (includes the above link, on page) : http://www.penmachine.com/techie/airport1400.html