You can take a look here
http://atmelwlandriver.sourceforge.net
which is the driver I use for my pcmcia card on my laptop (Belkin F5D6020 ver. 2; version 1 is an entirely different chipset with great Linux support, which is what I thought I was getting), but is also supposed to support some of the USB devices based on this chipset family. You can also look here
http://at76c503a.berlios.de/
which supports some devices that the other driver doesn't (at least not any longer). Neither driver is supposed to be terribly mature. When I first tried the "stable" version of the first driver for my laptop, it didn't work right, but then I tried the then latest snapshot, and it has worked great for what I need at my house.