Show list of custom posts with respective attachments?

Trust us on this one, you want to use WordPress’ query solution. It provides a whole bunch of awesome extras, such as object caching, autoloading of metadata, etc. Plus, it’s almost guaranteed to be forwards compatible.

So. How to do what you’ve inquired about. Something like this ought to do the trick:

<?php
$podcasts = new WP_Query( array(
  'post_type' => 'podcasts',
  'posts_per_page' => 10, // the number of podcasts you want to show. use -1 for all of them.
));
foreach ( $podcasts as $podcast ) {
  $attachment = get_posts('post_type=attachment&post_status=inherit&post_parent=".$podcast->ID);
  if ($attachment) {
    $attachment = $attachment[0];
    ?>
    <li><?php echo get_the_title( $podcast->ID ); ?> - <?php echo wp_get_attachment_url( $attachment->ID ); ?></li>
    <?php
  }
}
?>