greenprimary:
If you can get your hands on one definately get an Orinoco Gold card.
It will work perfectly with all the WiFi goodies: Airsnort, Kismet etc.
I run a WiFi website and many of us are Knoppix/Knoppix-STD users and all run Gold cards with great success.
For any ?'s/tips/tricks on Wireless w/Knoppix fell free to browse my forums.

--r00t