NDiswrapper is the way forward i believe. It works by loading the windows driver, and wrapping it for use by linux. An ugly solution, but the only way to go for some cards. It seems yours is supported
Card: NETGEAR WG121 Wireless USB2.0 Adapter
Chipset: Prism54 (I don't know more)
Driver: WG121 Software Version 2.0, NETGEAR Inc.,03/09/2004, from http://www.netgear.com
Other: Seems to work well. I had to upload the new firmware by running the installation on WinXP, but now it works. If anyone knows another way, please edit this. I used the drivers in the ndis5-directory of the unzipped download.
for installation instructions.