After you have deleted the sections above, in the "div id homepagebottom" section that remains, look for:
Code:
<?php $recent = new WP_Query("cat=63&showposts=4"); while($recent->have_posts()) : $recent->the_post();?>
Replace "cat=63" with your category number and change the "showposts=4" to "showposts=1"
Hope that helps :)