You need to install the kenel sources when creating modules for your kernel version. You also need to be in /usr/src/linux when
issuing the make clean modules command.

However you are using an older version of Knoppix and if you download Knoppix 5.1.1 it will have kernel 2.6.19
You may find that the modules are updated and your card will work. If you have broadband why not download knoppix and see if the card is detected from the live cd?