var rector=5
var stopit=0 
var a=1

function init(which){
  stopit=0
  shake=which
  shake.style.left=0
  shake.style.top=0
}

function rattleimage(){
  if ((!document.all&&!document.getElementById)||stopit==1)
  return
  if (a==1){
    shake.style.top=parseInt(shake.style.top)+rector
  }
  else if (a==2){
    shake.style.left=parseInt(shake.style.left)+rector
  }
  else if (a==3){
    shake.style.top=parseInt(shake.style.top)-rector
  }
  else{
    shake.style.left=parseInt(shake.style.left)-rector
  }
  if (a<4)
  a++
  else
  a=1
  setTimeout("rattleimage()",50)
}

function stoprattle(which){
  stopit=1
  which.style.left=0
  which.style.top=0
}

//full source code c Dynamic Drive (www.dynamicdrive.com)