Trying to find a cheap wireless solution for my old iMac DV, I picked up a DWL-G122 ver. B1. After reading all of the information above, I first tried installing the Railink drivers and they worked just fine, but they were a bit clunky to work with. I then uninstalled them and installed the ones on the driver CD. They work perfectly. The installer adds a new preference pane and it also adds a nice signal strength gauge by the clock. A few hints...

The dongle will not start up initially until you set your network up in the preference pane.

Use a static IP address; When your Mac starts up, the network initialization tries to negotiate a dynamic address before the dongle starts up and you get a random address. Using a static address fixes this.

Also, for some reason, the driver(?) will sometimes take up to a minute to load and start the dongle on system startup.

I'm running it on an iMac DV and OS 10.3.9.