http://www.seattlewireless.net/index.cgi/WirelessDriver
This site has been remarkably helpful to us I believe - there is compilable sourcecode for OSX 10.4 for Orinoco/Prism Cards.
Installing the binary they provided did not work - but they do provide the source to this binary, and I believe this could be the key if someone could try compiling it in Xcode (or perhaps provide me with instructions - I have the dev kit, but haven't opened it up).
Here's a direct link to the source: http://www.wwc.edu/~frohro/WirelessCard.zip
