The actual function as described in the tutorial on mah blog.

top_artists

function top_artists(){
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.open("GET","http://ws.audioscrobbler.com/2.0/user/BDORN/weeklyartistchart.xml",false);
xmlhttp.send();
xmlDoc=xmlhttp.responseXML; 
var x=xmlDoc.getElementsByTagName("artist");
for (i=0;i<8;i++)
  { 
  document.write("<li>");
  document.write("<a href='");
  document.write(x[i].getElementsByTagName("url")[0].childNodes[0].nodeValue);
  document.write("'>");
  document.write(x[i].getElementsByTagName("name")[0].childNodes[0].nodeValue);
  
  document.write(" (");
  document.write(x[i].getElementsByTagName("playcount")[0].childNodes[0].nodeValue);
  document.write(")");
  
  document.write("</a>");
  document.write("</li>");
  }
}