WordPress MU

Can someone tell me why this doesn't work like I'd expect it to?

function wp_list_main_blog_pages($arg) {
	global $wpdb,$blog_id;
	$wpdb->set_blog_id(1);
	wp_list_pages($arg);
	$wpdb->set_blog_id($blog_id);
}

It outputs the pages from the main blog but it doesn't set the blog id back to the current blog.

basically trying to do the same thing as this but with less coding:
http://dustyreagan.com/global-page-navigation-accross-wordpress-mu-blogs/

<?php switch_to_blog(1);
wp_list_pages($arg);
restore_current_blog(); ?>

(roughly)

work's perfect thanks.. now I have to get the main blog id from path for each site.

this should work assuming the dashboard blog is the main blog:
get_site_option(dashboard_blog);