window.attachEvent("onload", alphaBackgrounds); 

function alphaBackgrounds() // correctly handle PNG "BACKGROUNDCOLOUR" transparency in Win IE 5.5 or higher. 
{ 
    var rslt = navigator.appVersion.match(/MSIE (\d+\.\d+)/, ''); 
    var itsAllGood = (rslt != null && Number(rslt[1]) >= 5.5); 
    for (i=0; i<document.all.length; i++){ 
        var bg = document.all[i].currentStyle.backgroundImage; 
        if (itsAllGood && bg){ 
            if (bg.match(/\.png/i) != null){ 
                var mypng = bg.substring(5,bg.length-2); 
                document.all[i].style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+mypng+"', sizingMethod='scale')"; 
                document.all[i].style.backgroundImage = "url('img/blank.gif')"; 
            } 
        } 
    } 
}