Link Master --> Word Press home page only

<?php if(is_home() && $post==$posts[0] && !is_paged()) { ?>
     PLACE ADVERTISEMENT HERE.
<?php } ?>



<?php query_posts('cat=3&showposts=1'); ?>
<?php while (have_posts()) : the_post(); ?>
<h1>Featured Topic</h1>
<Strong><?php the_title(); ?></strong>
<p><?php the_content_limit(500,""); ?></p>
<a href="<?php the_permalink() ?>">Click to learn more</a>
<?php endwhile;?>