Version 6.2 of Knoppix just released does a much better job of detecting and configuring WLAN hardware than any version I have used before. My ASUS EeePC 900 came straight up, no fiddling. Connecting to wireless networks is almost identical to Ubuntu, must use the same configuration software.

If you still have no joy, then setup a spare wireless router as a client bridge and plug a wire into that. Use DD-WRT on the router. Ugly but it will work.