How to add jQuery to Joomla ?

The Joomla 1.5 is coming with Mootools therefore you might experience some conflict with jQuery now.
Just follow the way below to avoid any conflicts. Add the following lines to your view.html.php.

$document = &JFactory::getDocument();
$document->addScript( 'http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js' );
$document->addCustomTag( '' ); 

The above code fragment would solve your problem.