I guess this issue is solved by now, but in case others find there way here I would like to point out that I believe that the reason why Christian had an empty page was because his require_once and define was in the wrong order. The default index.php for WP looks like this:
<?php
/* Short and sweet */
define(‘WP_USE_THEMES’, true);
require(‘./wp-blog-header.php’);
?>
so in his case the following probably would have worked
<?php
/* Short and sweet */
define(‘WP_USE_THEMES’, true);
require(‘blo/wp-blog-header.php’);
?>
a simple one would look like this:
<?php
define(‘WP_USE_THEMES’, false);
require_once(‘blog/wp-blog-header.php’);
get_header(); ?>
<div id=”page”>
<div id=”content”>
Welcome to xyz.com
</div>
<?php get_sidebar(); ?>
</div>
<?php get_footer(); ?>
?>