<li id="meta" class="widget-container">
<h3 class="widget-title"><?php _e( 'Popular Posts', 'twentyten' ); ?></h3>
<?php
    $pop_posts = 5;
    $popularposts = "SELECT $wpdb->posts.ID, $wpdb->posts.post_title,  COUNT($wpdb->comments.comment_post_ID) AS 'stammy' FROM $wpdb->posts, $wpdb->comments WHERE comment_approved = '1' AND $wpdb->posts.ID=$wpdb->comments.comment_post_ID AND post_status = 'publish' AND comment_status = 'open' GROUP BY $wpdb->comments.comment_post_ID ORDER BY stammy DESC LIMIT ".$pop_posts;
    $posts = $wpdb->get_results($popularposts);
    if($posts){
        foreach($posts as $post){
        $post_title = stripslashes($post->post_title);
        $guid = get_permalink($post->ID);
        $thumb = get_post_meta($post->ID,'_thumbnail_id',false);
        $thumb = wp_get_attachment_image_src($thumb[0], 'post-thumbnail', false);
        $thumb = $thumb[0];
?>

        <div class="twentyten-popular-post">
            <?php if ($thumb) { ?>
                <img src="<?php echo $thumb; ?>" width=40 height=40 />
            <?php } ?>
            <a href="<?php echo $guid; ?>" title="<?php echo $post_title; ?>"><?php echo $post_title; ?></a>
        <div class="clear"></div>
        </div>
        <?php }
    }
?>
</li>