how to go past the post limit for thumbnail archive?

i’m using an array of thumbnails and i keep getting lots of repeats, any suggestions?

here’s the code i’m using

‘
<?php
//for category archives
$categoryvariable=$cat; // assign the variable as current category
$query= ‘cat=’ . $categoryvariable. ‘&orderby=date&order=DSC’. ‘&showposts=100’; // concatenate the query
query_posts($query); // run the query
?>

<?php
//for date archives
query_posts($query_string . ‘&showposts=-1’); ?>

<?php while (have_posts()) : the_post(); ?>

<?php
//Get images attached to the post
$args = array(
‘post_type’ => ‘attachment’,
‘post_mime_type’ => ‘image’,
‘numberposts’ => -1,
‘order’ => ‘ASC’,
‘post_status’ => null,
‘post_parent’ => $post->ID
);
$attachments = get_posts($args);
if ($attachments) {
foreach ($attachments as $attachment) {
$img = wp_get_attachment_thumb_url( $attachment->ID );
break; }
//Display image
} ?>

” title=”<? the_title(); ?>”><img class=”thumbarch” src=”<?php echo $img; ?>” alt=” ” />

<?php endwhile; ?>’