<?php   $values = get_post_custom_values("thumbnail");
                  if (isset($values[0])) { ?>
                <a href="<?php the_permalink() ?>" rel="bookmark" >
                <img src="<?php echo bloginfo('template_url'); ?>/scripts/timthumb.php?src=<?php echo get_option('home'); ?>/<?php $values = get_post_custom_values("thumbnail"); echo $values[0]; ?>&w=150&h=100&zc=1&q=100;" alt="<?php the_title(); ?>" class="left" />
                </a>
           <?php } elseif( get_the_post_thumbnail($post->ID) ) { ?>
<a href="<?php the_permalink() ?>" rel="bookmark" >
<?php the_post_thumbnail(); ?>
</a>
<?php } ?>