How to have the first post look different

Hey, I have a theme that requires the first post of index.php to look different. Is there any way to achieve this?

The first post needs to look like:

<div class="boxcontents">
<h2 class="posttitle"><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><?php the_title(); ?></a></h2>
<?php the_content('Read the rest of this entry &raquo;'); ?>
</div>
</div>

and the next posts need to be like this:

<div class="box">
<div class="boxcontents">
<h2 class="posttitle"><a>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><?php the_title(); ?></a></h2>
<?php the_content('Read the rest of this entry &raquo;'); ?>
</div>
</div>