Wordpress : A Page of Posts

get_header(); ?>

<div id="content" class="narrowcolumn">

<?php
// page id 21 will get category ID 12 posts, page 16 will get category 32 posts, page 28 will get category 17 posts
if (is_page('21') ) {
$cat = array(12);
} elseif ( is_page('16') ) {
$cat = array(32);
} elseif ( is_page('28') ) {
$cat = array(17);
} else {
$cat = '';
}

$showposts = -1; // -1 shows all posts
$do_not_show_stickies = 1; // 0 to show stickies
$args=array(
'category__in' => $cat,
'showposts' => $showposts,
'caller_get_posts' => $do_not_show_stickies
);
$my_query = new WP_Query($args);

?>

<?php if( $my_query->have_posts() ) : ?>

<?php while ($my_query->have_posts()) : $my_query->the_post(); ?>
<?php
//necessary to show the tags
global $wp_query;
$wp_query->in_the_loop = true;
?>
<div <?php post_class() ?> id="post-<?php the_ID(); ?>">
<h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2>
<small><?php the_time('F jS, Y') ?> <!-- by <?php the_author() ?> --></small>

<div class="entry">
<?php the_content('Read the rest of this entry »'); ?>
</div>

<p class="postmetadata"><?php the_tags('Tags: ', ', ', '<br />'); ?> Posted in <?php the_category(', ') ?> | <?php edit_post_link('Edit', '', ' | '); ?> <?php comments_popup_link('No Comments »', '1 Comment »', '% Comments »'); ?></p>
</div>

<?php endwhile; ?>

<?php else : ?>

<h2 class="center">Not Found</h2>
<p class="center">Sorry, but you are looking for something that isn't here.</p>
<?php get_search_form(); ?>

<?php endif; ?>

</div>

<?php get_sidebar(); ?>