// We dont want the try adding the tracking code until the page links are loaded
if (document.addEventListener)
{
  document.addEventListener("DOMContentLoaded", addEvents, null); // Firefox
} 
else
{
  addEvents(); // IE : Call the function immediately because the script is referenced with the defer attribute supported by IE
}

function addEvents()
{
  // quit if this function has already been called
  if (arguments.callee.done) 
    return;
  // flag this function so we don't do the same thing twice
  arguments.callee.done = true;
  for (i=0; i <document.links.length; i++)
  {
    var x = document.links[i];
    // Only attach tracking code to specific file types
    var extensions = new RegExp(".+\.(zip|exe|dmg|pdf|xls|doc|csv|txt|ppt|xml|rtf)$");
    var doc = x.href.toLowerCase().match(extensions);
    if (doc)
    {
      if (x.attachEvent)
      {
        x.attachEvent('onclick', function () {TrackIt(window.event.srcElement)}); // IE
      } 
      else 
      {
        x.addEventListener('click', function () {TrackIt(this)}, false); // Firefox
      }
    }
  }
}

function TrackIt(link)
{
  // Remove the conversion to Lowercase if you are on a Case sensitive web server
  urchinTracker(link.href.toLowerCase());
}