With the help of this newsgroup and Google I have got this code
working fully in Firefox and can alert the XML in IE but because IE
does not impliment the DOM "getElementsByTagNameNS()" function I
cannot read the individual rates from the Cube namespace.

Is there a wrapper or some other relatively simple method of getting
IE to do what in Firefox is straighforward?

Here is the code. Any help gratefully received.

var doc
function load() {
   if (document.implementation &&
document.implementation.createDocument){
		doc = document.implementation.createDocument("", "", null);
		doc.load('CEBrates.xml');
		doc.onload = createTable;
	}
	else if (window.ActiveXObject){
		var doc1 = new ActiveXObject("Microsoft.XMLDOM");
      function loadXML(xmlFile){
         doc1.async="false";
         doc1.onreadystatechange=verify;
         doc1.load(xmlFile);
         doc=doc1.documentElement;
      }
      loadXML('CEBrates.xml');
      alert(doc.xml)
      }
      else {
		alert('Your browser can\'t handle this script');
		return;
     }
}
function verify() {
    if (doc1.readyState != 4 ){
        return false;
   }
}
function createTable() {
    var cubes = doc.getElementsByTagNameNS('http://www.ecb.int/
vocabulary/2002-08-01/eurofxref','Cube');
    var dateRate = cubes[1].getAttribute('time');
    var dateRateSplit = dateRate.split('-');
    for (var i = 2; i < cubes.length; i++){
        var currency = cubes[i].getAttribute('currency');
        var rate = cubes[i].getAttribute('rate');
        rateObject[currency] = rate;
    }
    document.getElementById('boldStuff').innerHTML = dateRateSplit[2]
+ "." + dateRateSplit[1] + "." + dateRateSplit[0];
    document.getElementById("currency").value = "GBP";
    getRates();
};
 var rateObject = {};
function getRates() {
    var curr= document.getElementById("currency").value;
    var currRate = rateObject[curr];
    var currStatement= "1 EUR = " + currRate + " " + curr ;
    document.getElementById("rate").value=currStatement;
    var currRev=1/currRate;
    currRevFix=currRev.toFixed(5);
    var currRevStatement= "1 " + curr +"= " + currRevFix + " EUR";
    document.getElementById("rateRev").value=currRevStatement;
};