Show logo and tag line below only

Try replacing the //Prepare Header php snippet in page.tpl with this:

          // Prepare header
          $site_fields = array();
          if ($site_name) {
            $site_fields[] = check_plain($site_name);
          }
          if ($site_slogan) {
            $site_fields[] = check_plain($site_slogan);
          }
          $site_title = implode(' ', $site_fields);
          $site_fields[0] = '<span>'. $site_name .'</span>';
//          $site_fields[1] = '<span id="slogan">'. $site_slogan .'</span>';
          $site_html = implode(' ', $site_fields);

          if ($logo || $site_title) {
            print '<h1><a href="'. check_url($base_path) .'" title="'. $site_title .'">';
            if ($logo) {
              print '<img src="'. check_url($logo) .'" alt="'. $site_title .'" id="logo" />';
            }
            print $site_html .'</a></h1>';
          }
        

Er... I think i misunderstood what you were trying to do. You can always just "hard code" the logo and tagline into page.tpl directly by replacing the //Prepare header function with <img> and <h1> tags. I'll look into the functionality of the //Prepare header function to make sure it is working as it is indented.