function TW_imageSwap(Image, Src){
  var objStr,obj;
 
  if(document.images){

    if (typeof(Image) == 'string') {

      objStr = 'document.' + Image;
      obj = eval(objStr);
      obj.src = Src;
    } else if ((typeof(Image) == 'object') && Image && Image.src) {
      Image.src = Src;
    }
  }
}