Unique post formatting by category

Hi There,
I’m a PHP noob, and I’m afraid the codex wasn’t much help either. Basically what I want to do is this: On my index display posts with a category of 31 (remaindered links) without a title category, or comments (the top and bottom pretty much.) Then I want to display all other categories normally. Here’s the code I currently have in place:

<?php $posts = get_posts( "numberposts=10" ); ?>
    <?php if (have_posts()) : while (have_posts()) : the_post(); ?>
		<div class="post" id="post-<?php the_ID(); ?>">
		<p>testing testing 123</p>
		<h2><?php the_title(); ?></h2>
			<div class="entrytext">
				<?php the_content('<p class="serif">Read the rest of this page &raquo;</p>'); ?>

				<?php link_pages('<p><strong>Pages:</strong> ', '</p>', 'number'); ?>

			</div>
		</div>
	  <?php endwhile; endif; ?>
	<?php edit_post_link('Edit this entry.', '<p>', '</p>'); ?>