two category drop down search filter php help!

I’m working on a wordpress website using this search facility:

http://spruce.it/noise/two-category-dropdown-search-filter-in-wordpress/

All is working OK but in the last few lines I want to include a line to say that if there are no posts in the two categories, e.g. dentists in brighton to show a ‘there are no posts’ kind of message. My php is very limited and what I’ve tried doesn’t work. Any pointers much appreciated!

I’ve copied the whole page below but it’s the last few lines really that are where it’s all happening …

<?php
require_once('../../../wp-blog-header.php');

if (($_GET['category'] != -1) && ($_GET['city'] != -1)):
$paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
query_posts(
array(
  'orderby' => 'date',
  'order' => 'DESC',
  'paged' => $paged,
  'posts_per_page' => 6,
  'category__and' => array(
     $_GET['city'],
     $_GET['category']
  ),
)
);
?>

<?php get_header(); ?>
<div id="main">
<div id="content" class="wide">
        <?php if (have_posts()) : ?>

       <h1><?php echo get_cat_name($_GET['category']) ?>,
<?php echo     get_cat_name($_GET['city']) ?></h1>

         <?php remove_filter ('the_content1', 'wpautop'); ?>
         <h2>These <?php echo get_cat_name($_GET['category']) ?> can help you. They       service businesses in <?php echo get_cat_name($_GET['city']) ?><?php if(   is_category('exeter') ) echo get_page_content(585);
        elseif( is_category('birmingham') ) echo get_page_content(587); 

elseif( is_category('') ) echo '.';?>
       </h2>

             <ul id="search1"><?php while (have_posts()) : the_post(); ?  >

               <a href="http://www.<?php echo get_post_meta($post->ID, 'URL', true); ?>"   title="Go to the URL:  www.<?php echo get_post_meta($post->ID, 'URL', true); ?>" target="_blank">
               <li id="<?php echo get_post_meta($post->ID, 'AdSize', true); ?>"><h5><?php the_title(); ?></h5>
                <?php the_post_thumbnail( $size, $attr ); ?>
            <div class="doubler"><?php the_content(''); ?>
                <p>Tel: <?php echo get_post_meta($post->ID, 'Telephone', true); ?><br />Website: www.<?php echo get_post_meta($post->ID, 'URL', true); ?></p></div>
                 </li>
                 </a>

                <?php endwhile; ?></ul>  

                <?php endif; ?>  

<div class="localhelp">
<h1>Find Local Help</h1>

<form method="get" id="sponsorsearchform" action="<?php bloginfo('template_url');? >/findsponsor.php" >
 <?php wp_dropdown_categories('show_option_none=Select a Category&hide_empty=1&child_of=14&orderby=name&name=category'); ?>
<?php wp_dropdown_categories('show_option_none=Select a Location&hide_empty=1&child_of=13&orderby=name&name=city'); ?>
<input type="submit" value="Search"/>
</form>

</div>        

   <hr />   

<?php comments_template(); ?>

    </div><!--end content-->

</div><!--end main-->
<?php get_footer(); ?>     

<?php else:
if ($_GET['category'] != -1){
$currentCat = get_category($_GET['category']);
if ($currentCat->category_count > 0) {
    header('Location:'.get_category_link($_GET['category']));
} else {
    echo "No result found!";
}
} elseif ($_GET['city'] != -1){
$currentCity = get_category($_GET['city']);
if ($currentCity->category_count > 0) {
    header('Location:'.get_category_link($_GET['city']));
} else {
    echo "No result found!";
}
} else{
 header('Location: http://www.test.com');
}
endif;?>