I have a Netgear WG511T which (I think) has the same chipset. It boots up OK and sometimes runs using madwifi (the version on Knoppix 4.0.2) but eventually it loses contact with the AP. If I fiddle with it enough, trying to get it running again, I can hang the whole system.

Did we get later revisions of madwifi in the 5.0 or 5.0.1 releases?