Most commented posts of the last 7 days

Hi guys,

i’m using the following code to determine the most commented posts of the last 7 days:

<?php
$weekstart = date('Y-m-d', strtotime('-7 days'));
$query = $wpdb->prepare("
  SELECT comment_post_id, count( comment_post_id ) AS c, SUBSTRING( comment_date, 1, 10 ) AS d
  FROM        $wpdb->comments
  WHERE       (comment_date >= %s)
  GROUP BY comment_post_id
  ORDER BY c DESC , d DESC
  ",$weekstart);
$col_ids = $wpdb->get_col($query);
if ($col_ids) {
  $postids = implode($col_ids,', ');

  function filter_orderby($orderby = '') {
    global $postids;
    $orderby = " FIELD(ID,$postids )";
    return $orderby;
  }

  add_filter('posts_orderby', 'filter_orderby');  //need this filter so posts get returned in the order we specify

  $args=array(
    'post__in' => $col_ids,
    'caller_get_posts'=>1
  );
  $my_query = null;
  $my_query = new WP_Query($args);
  if( $my_query->have_posts() ) {
    echo 'List of Posts with most comments in last 7 days';
    while ($my_query->have_posts()) : $my_query->the_post(); ?>
      <p><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></p>
      <?php
    endwhile;
  }
  remove_filter('posts_orderby', 'filter_orderby');
  wp_reset_query();  // Restore global post data stomped by the_post().
}
?>

– Source

I was wondering if you guys could improve it a little as i don’t have the skills for it.
For example comments marked as spam are messing up the results as their posts get counted until i delete the spam.

Your help is very appreciated.