Links in menu with domain name
If you are just trying to create links to pages within your Drupal site you can use relative paths and when Drupal renders the link it will show as a complete URL.  You only need to have the domain name in the path when you are linking to an external site (not the same domain)

Example, to link to the Site Configuration admin page:

Use admin/settings instead of http://localhost/admin/settings and it will still show up in your menu as a full URL.