you need the ipw2100 driver, what knoppix version are you using? it should be on the cd.
Do lsmod and see if ipw2100 is loaded, if so you may just need to run netcardconfig to do dhcp.
if ipw2100 is not loaded try as root modprobe ipw2100, then netcardconfig, it will likely be eth1.

if all fails get newest knoppix or better yet, get Kanotix.