Carp,
The reason why I didn't use a relative url is because my development database is two levels under my live site. I referenced it by {$xcart_web_dir} or rather I did when it worked before.
Your suggested code takes me straight to my live site when I click on the home link.
I tried this and it worked ok for my dev site although the only diff now is the full path is in variable instead of hard coded in the template.
<li><a href="{$http_location}">Home</a></li>
<li><a href="{$http_location}/help.php?section=contactus&mode=update">Contact Us</a></li>
<li><a href="{$http_location}/register.php">Register</a></li>
<li><a href="{$http_location}/help.php?section=login">My Account</a></li>