download_metric = function(tag, client) {
    (new Image).src="http://tr.foxmarks.com/tracking/impressions.gif" +
    "?app=download" + 
    "&tracking=download" + 
    "&client=" + client + 
    "&dest=" + encodeURIComponent(tag.href) +
    "&no_cache=" + (new Date).getTime();
    return true;
}