i want to get a event that will fire when i click inside a td of a html table

i had this:

 ('td').live('click', function() {
            alert($(this).attr('id'));
        });

which works but this fires inside the 'th" cells as well (not sure why).

is there any selector that just fires inside td's and not th's. I tried this:

 ('tbody td').live('click', function() {
            alert($(this).attr('id'));
        });

but that didn't seems to stop this firing for the th's.