window.onload = setpng; 
function setpng(){ 
  var arVersion = navigator.appVersion.split("MSIE") 
  var version = parseFloat(arVersion[1]) 
    if ((version >= 5.5) && (document.body.filters)) { 
      for(var i=0; i<document.images.length; i++){ 
        var img = document.images[i]; 
        var imgName = img.src.toLowerCase(); 
        if (imgName.substring(imgName.length-3, imgName.length) == "png"){ 
          img.src="img/blank.gif"; 
          img.runtimeStyle.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='" + imgName + "',sizingMethod='scale')"; 
        } 
      } 
    } 
}