Fatal Error msg after upgrading to 2.5

My blog now comes up as this message after upgrading to 2.5.

Fatal error: Call to undefined function wp() in /home/nestboxc/public_html/blog/wp-blog-header.php on line 18

I’ve checked the wp-config file and it contains the correct information (pointing to mySQL databaseas before the upgrade). I’m at a total loss as to what to do. I tried creating a new db, put a fresh installation of WP 2.5 on that but am unable to transfer the information from my old database to the new one. As you can tell, my knowledge of how to handle this is quite lacking. Please help!

Here’s what the wp-blog-header.php file looks like:

<?php

if (! isset($wp_did_header)):
if ( !file_exists( dirname(__FILE__) . ‘/wp-config.php’) ) {
if (strpos($_SERVER[‘PHP_SELF’], ‘wp-admin’) !== false) $path = ”;
else $path = ‘wp-admin/’;

require_once( dirname(__FILE__) . ‘/wp-includes/classes.php’);
require_once( dirname(__FILE__) . ‘/wp-includes/functions.php’);
require_once( dirname(__FILE__) . ‘/wp-includes/plugin.php’);
wp_die(“There doesn’t seem to be a wp-config.php file. I need this before we can get started. Need more help? We got it. You can create a wp-config.php file through a web interface, but this doesn’t work for all server setups. The safest way is to manually create the file.</p><p>Create a Configuration File“, “WordPress › Error”);
}

$wp_did_header = true;

require_once( dirname(__FILE__) . ‘/wp-config.php’);

wp();

require_once(ABSPATH . WPINC . ‘/template-loader.php’);

endif;

?>