function opacity(id, opacStart, opacEnd, millisec) {
  //speed for each frame
  var speed = Math.round(millisec / 100);
  var timer = 0;

  //determine the direction for the blending, if start and end are the same nothing happens
  if(opacStart > opacEnd) {
      for(i = opacStart; i >= opacEnd; i--) {
          setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
          timer++;
      }
  } else if(opacStart < opacEnd) {
      for(i = opacStart; i <= opacEnd; i++)
          {
          setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
          timer++;
      }
  }
} 

function changeOpac(opacity, id) {
  var objectReal = document.getElementById(id);
  var object = document.getElementById(id).style;
  try{object.opacity = (opacity / 100);}catch(e){}
  try{object.MozOpacity = (opacity / 100);}catch(e){}
  try{objectReal.filters.alpha.opacity = (opacity / 100);}catch(e){}
  try{object.KhtmlOpacity = (opacity / 100);}catch(e){}
  try{object.setProperty("-khtml-opacity", (opacity / 100), null);}catch(e){}
  try{object.filter = "alpha(opacity=" + opacity + ")";}catch(e){}
}