This is a great top nav hack. But, if you have pages with sub-pages underneath, it breaks all over the place.
But I emailed the author for a fix for this, and he sent me this code, which only shows the 1st level page titles.
Find this code:
<?php wp_list_pages('title_li='); ?>
Then replace it with:
<?php wp_list_pages('depth=1&title_li='); ?>
The depth is to set how many level of pages to be displayed in the
list. Enjoy.