Using jQuery with Magento Including Protype, Scriptaculous etc...

How to use jQuery with Magento?

Download jQuery from jQuery site

Add this line to the bottom of jQuery.js

jQuery.noConflict();

Copy the file to the js/jquery folder|directory

In page.xml, add it to the list of js files as:

<action method="addJs"><script>jquery/jquery-1.2.6.noConflict.min.js</script></action>

or,

<action method="addItem"><type>js</type><name>jquery.js</name><params/></action>

How to use jQuery with magento now?

The below procedure is one way.

jQuery(document).ready(function($){
// Use jQuery with $(...)
$('div').show();
});
// Use Prototype with $(...)
$('id').hide();

note: $ sign inside function($).

And another procedure is,

jQuery(document).ready(function(){
// Use Prototype with $(...)
$('id').hide();
// Use jQuery with jQuery(...)
jQuery('div').show();
});

There are few more procedures available at jQuery site. But this much information is good to go with using jQuery with magento which uses prototype, scriptaculous etc...