I spent the day searching for information and a driver for the D-Link Wireless G USB adapter for a recently purchase iMac G3 running OS X Panther. There is no support from D-Link; however, I stumbled upon a MacWireless driver available through Ralink.
http://www.ralinktech.com/supp-1.htm
I installed the driver, plugged in the USB adapter, and it all works. I also tested it on my Powerbook G4. Worked fine!
Hope this saves someone some time.
Thanks you for this information.
Regards
Philippe