It depends on your theme and WP version (you’re using 2.9.1 – you should consider upgrading).
You can:
- upgrade to V3+ to use the menu editor
that’s built in (recommended) more
info:
http://templatic.com/news/wordpress-3-0-menu-management - hard code your theme template with
the link added to the end in the HTML - modify the theme call to
wp_list_pages() function excluding
your contact page link (see:
http://codex.wordpress.org/Template_Tags/wp_list_pages)