Joomla! 1.5 doesn't automatically add your site's name in the page title that appears in your browser (upper left next to the browser icon).
For example, if you have an About Us page, it might show this "out-of-the-box":
About Us
If you site name is added, it might show:
About Us - Your Organization Here
To add your site name, you can include the following in your Joomla! index.php template file:
<?php
$mydoc =& JFactory::getDocument();
$mytitle = $mydoc->getTitle();
$conf =& JFactory::getConfig();
$sitename = $conf->getValue('config.sitename');
$mydoc->setTitle($mytitle.' - '.$sitename);
?>
Adapted from http://www.howtojoomla.net/2008060586/how-tos/templates/how-to-display-y...