To use opacity in all versions of IE, the order is:
.transparent-element {
/* for IE 8 & 9 */
-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=60)"; // IE8
/* works in IE 8 & 9 too, but also 5, 6, 7 */
filter: alpha(opacity=60); // IE 5-7
/* Modern Browse...