I can’t get index.php to only show 1 post! WP 2.1

This worked before but now it doesn’t! Can someone tell me what I am doing wrong?

<?php query_posts('category_name=Featured&showposts=1');// WP_Query("showposts=1");
          while (have_posts()) : the_post();
           $do_not_duplicate = $post->ID;?>

    <!--
		<?php trackback_rdf(); ?>
		-->
    	<div class="post" id="post-<?php the_ID(); ?>">
      		<h2><a href="<?php the_permalink() ?>" rel="bookmark" title="<?php the_title(); ?>"><?php the_title(); ?></a></h2>
      		<div class="postcontent">
	  			<p><?php the_excerpt(); ?>  </p>
      		</div>
		</div>
 	<?php endwhile; ?>