192.168.2.x looks good for a private IP range, and the fact that you can connect to your router seems to indicate that your address is OK. You haven't mentioned if you had configured DNS. Without it, you won't be able to do much. I suggest you try DHCP first, which should take care of providing your linux client with all the necessary parameters (IP, netmask, DNS servers...). Once that works and if you really need a static IP, make sure you provide all the parameters when asked by the knoppix "netcardconfig" script. If you've installed to HD, look into /etc/network/interfaces and /etc/resolv.conf

BTW PPPoE is perfectly supported on linux, by the "roaring penguin" SW, included with knoppix. Connecting through USB can be problematic, though, and purchasing a router is a smart move.