i got knoppix 5.0.1 network working ,i did the following :

in terminal mode as root :

ifconfig eth0 up
route add default gw 111.111.111.111 (the ip address you assign to your gateway or modem)

if you have 2 or more networks take out the word DEFAULT for the rest of the networks( route add gw 111.111.111.2) . But i have to do this every time i boot up.