dr.brems

open the plugin file: “wp_related_posts.php” and search for:

$related_posts as $related_post

and replace:

if ($wp_rp["wp_rp_thumbnail"]){
			$output .=  '<a href="'.get_permalink($related_post->ID).'" title="'.wptexturize($related_post->post_title).'"><img src="'.get_post_meta($related_post->ID, $wp_rp["wp_rp_thumbnail_post_meta"], true).'" alt="'.wptexturize($related_post->post_title).'" /></a>';
		}

with:

if ($wp_rp["wp_rp_thumbnail"]){
			$article_thumbnail = wp_get_attachment_image_src ( get_post_thumbnail_id ( $related_post->ID ), 'product_preview');
			$output .=  '<a href="'.get_permalink($related_post->ID).'" title="'.wptexturize($related_post->post_title).'"><img src="'.$article_thumbnail[0].'" width="'.$article_thumbnail[1].'" height="'.$article_thumbnail[2].'" alt="'.wptexturize($related_post->post_title).'" /></a>';
		}

now the plugin uses the article thumbnail..

cheers Dr.Brems