yes yes yes
MAC address filtering is a a very weak form of protection: the MAC address is transmitted in clear - any scanner can detect it and since it is trivial to change a MAC address (most forms of Unix including Linux come with this ability) you leave yourself wide open. I in fact don't even bother with MAC address filtering but have implemented strong encryption using WPA. Even WEP - which is acknowledged to be crackable - is vastly better than MAC address filtering