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