+2  A: 

IE has a slightly different implementation of XML documents from other browsers, one of the differences being that in IE there is an xml property of the document.

If you want to serialize the XML into a string in all browsers, you can use the following:

function serializeXmlDoc(xmlDoc) {
    if (window.XMLSerializer) {
        return (new window.XMLSerializer()).serializeToString(xmlDoc);
    } else if (typeof xmlDoc.xml != "undefined") {
        return xmlDoc.xml;
    }
}
Tim Down
.xml is Microsoft XMLDOM extension, not available in other browsers normally.
airmanx86
Thank's to all of you.Special thanks to Tim Down for finding out the solution which worked for me.
Amit Shah