hide if on front page and on taxonomy pages
Try something like this:

&lt;?php
   function hook_preprocess_page(&amp;$variables) {
       if (drupal_is_front_page() || drupal_is_taxonomy()) {
           $variables['title'] = NULL;
       }
   }


Change hook to the name of your theme.  Based on your example, it looks like you're hacking core which isn't good. Create a subtheme and implement your custom themeing there.