Arranging posts problem

Hey i am using this code to display post excerpts on my home page

<div class="postarray">
<a class="posttitle" title="<?php the_title(); ?>" href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a>
<p class="meta"> <?php the_time('jS F Y') ?>//<?php the_category(', ') ?>//<?php the_author(); ?></p>
<?php the_post_thumbnail(array(300,9999), array ('class' => 'alignleft')); ?>
<p class="thumbtext"><?php the_excerpt(); ?> </p>
<div class="clear"></div>
</div>

This is my css

.postarray {width: 300px;height: auto;padding: 5px;border-bottom: solid 1px black;margin: 10px;vertical-align: baseline;float: left;display: block; }

i cant seem to get my posts to align like this >>
http://f.cl.ly/items/331l1l171a2S253N2T0p/Screen%20shot%202011-08-04%20at%2001.39.14.png

Any help would be appreciated , Thanks Matt