I tried that every which way but loose and could not get the thumb to work right. So.... this is what works with the help of a plugin called Get The Image. Close to what you posted but for some reason I just could not get it the thumbs to load.
Code:
<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
<?php get_the_image( array( 'meta_key' => 'feature_img', 'size' => 'medium', 'width' => '257', 'height' => '164', 'image_class' =>
'feature' ) ); ?>
<a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>" rel="bookmark"><?php the_title(); ?></a>
<div class="entry-summary">
<?the_excerpt(); ?>
</div>
</div>
<?php endwhile; endif; ?>