According to the guide at http://ubuntuforums.org/showthread.php?t=75451
your card is supported automatically and 'You only need to rebuild this module if you recompile the kernel'. Follow the guide if you have changed your kernel version, otherwise 'Configure your new ath0: under System->Administration->Networking'
If that doesn't work you may have the problems described at http://madwifi.org/ticket/808
so please post the output of the root commands