You’re nearly there, you just need to tell WP that you want to query posts as well as your Press CPT.
So:
query_posts( array( 'post_type' => array('posts', 'portfolio'), ...);
where portfolio is the name of your custom post type.
The relevant Codex page
[Update]
So this is how the query should look
<?php
$args = array('post_type'=>array('posts', 'portfolio'));
query_posts($args);
if ( have_posts() ) : while ( have_posts() ) : the_post();
?>