VoiD2008, you made my day!
I changed the if statement a little bit to
if ( (is_admin() && $pagenow=='edit.php') && !current_user_can( 'update_core' )) {
So I don’t have to know the name of the user. Only if the user has a very high privileg (like update_core) I will show him/her the entire list.
Thanks again for this quick and very good answer!
