Store HTML In XML File And Display With AJAX

I want to store the main content of my site (with it's HTML) in an XML file such as:

<?xml version="1.0" encoding="UTF-8"?>
<root>
<data>
<h3>Hello World</h3>
<p>Here is some content, blah...</p>
<p>Yet another paragraph</p>
</data>
<data>
<h3>Section 2</h3>
<p>More stuff to read</p>
</data>
</root>

And I want to load all the HTML in a data node via an onclick event. I've got the following basic AJAX code:

<script type="text/javascript">
<!--
function ajaxRead(file,node) {
var xmlObj = null;

if(window.XMLHttpRequest) {
xmlObj = new XMLHttpRequest();
} else if (window.ActiveXObject) {
xmlObj = new ActiveXObject("Microsoft.XMLHTTP");
} else {
return;
}

xmlObj. {
if(xmlObj.readyState == 4) {

var parentNode;
parentNode = xmlObj.responseXML.getElementsByTagName('data')[node]

updateObj('xmlObj', parentNode.firstChild.data);
}}

xmlObj.open ('GET', file, true);
xmlObj.send ('');
}

function updateObj(obj, data) {
document.getElementById(obj).innerHTML = data;
}
//-->
</script>

If I remove the HTML tags within the data node it works, but obviously there is no formatting, and its just all text. How can I load the HTML content into the div? Note: 'xmlObj' is the name of the div I'm trying to populate.