CodingForums.com - Help getting data out of responseXML

I want my javascript to recieve an xml page containing two bits html code to insert into various places in the page.

example xml page

Code:

 <?xml version="1.0" ?> 

  <root>

     <image><img src="images/image1.jpg" class="imageclass" /></image> 

    <exif>

<table>

<tr><td>Head</td><td>Data</td>

.....

<tr><td>Head</td><td>Data</td>

</table>

    </exif>

</root>

I am pretty confident that I am sucessfully reciving the file as I can get the following.

window.alert(ajaxreq.responseXML);
// displays "[object XMLDocument]" in firefox
// displays "[object]" in IE7

window.alert(ajaxreq.responseXML.xml);
// displays the contents of the xml file in IE7
// displays "undefined" in firefox

Seems so good so far....
But that is far as I can get.

When I try
window.alert(ajaxreq.responseXML.getElementsByTagName("image")[0].nodeValue);
//returns null in both IE and Firefox.....

Am I doing something wrong? How do I get the contents of <image> and <exif> nodes so that I can insert them into my page?