Do you want to add "Login" and "Register" links easily to Atahualpa Menu?
1) Download the plugin Page Links To, install and activate (it works fine with Wordpress 3.2.1)
2) Create a new empty page in Wordpress with the name "Login", and insert in the "Page Links To" field this link: http://www.yourdomain.com/wp-login.php
3) Create a new empty page in Wordpress with the name "Register", and insert in the "Page Links To" field this link: http://www.yourdomain.com/wp-login.php?action=register
That's all, fast and clean, no stupid widget and no hard modify to do.

Bye bye.