First up, Welcome to LQ
chmod and chgrp, along with chown will not work on non-linux filesystems (well at least windoze filesystems anyway) in linux, not like you are used to anyway. Instead, it has to be done during mounting of the partition that the files reside on, so look into your entry in fstab.
You are looking for adding a umask option, for more info search the boards and post back if you have more questions.
Cool