diff --git a/build/test/fx.html b/build/test/fx.html
index bdbcbf2c..050513a4 100644
--- a/build/test/fx.html
+++ b/build/test/fx.html
@@ -1,7 +1,9 @@
-<html>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" dir="ltr">
 <head>
-<title>Animation Test Suite</title>
-<script src="../dist/jquery.js"></script>
+	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
+	<title>Animation Test Suite</title>
+	<script src="../dist/jquery.js"></script>
 <style>
 div#tests h4 {
 	background: red;
@@ -232,8 +234,9 @@ $(document).ready(function(){
 				var cur_o = jQuery.attr(this.style, "opacity");
 				if ( cur_o !== "" ) cur_o = parseFloat( cur_o );
 
-				if ( (t_o == "hide"||t_o == "show") && cur_o != f_o )
+				if ( (t_o == "hide"||t_o == "show") && cur_o != f_o ) {
 					return msg(this, "Opacity not reset to " + f_o + ": " + cur_o);
+				}
 
 				if ( t_w == "hide" && this.style.display != "none" )
 					return msg(this, "Hiding, display not none: " + this.style.display);
diff --git a/src/fx/fx.js b/src/fx/fx.js
index f67747fd..163f0f65 100644
--- a/src/fx/fx.js
+++ b/src/fx/fx.js
@@ -462,7 +462,7 @@ jQuery.extend({
 			if ( !elem.orig ) elem.orig = {};
 
 			// Remember where we started, so that we can go back to it later
-			elem.orig[prop] = elem.style[prop];
+			elem.orig[prop] = jQuery.attr( elem.style, prop );
 
 			options.show = true;
 
@@ -479,7 +479,7 @@ jQuery.extend({
 			if ( !elem.orig ) elem.orig = {};
 
 			// Remember where we started, so that we can go back to it later
-			elem.orig[prop] = elem.style[prop];
+			elem.orig[prop] = jQuery.attr( elem.style, prop );
 
 			options.hide = true;
 
@@ -492,7 +492,7 @@ jQuery.extend({
 			if ( !elem.orig ) elem.orig = {};
 
 			// Remember where we started, so that we can go back to it later
-			elem.orig[prop] = this.style[prop];
+			elem.orig[prop] = jQuery.attr( elem.style, prop );
 
 			if(oldDisplay == "none")  {
 				options.show = true;
diff --git a/src/jquery/jquery.js b/src/jquery/jquery.js
index 061d86c8..0c00829f 100644
--- a/src/jquery/jquery.js
+++ b/src/jquery/jquery.js
@@ -1402,12 +1402,12 @@ jQuery.extend({
 
 	curCSS: function(elem, prop, force) {
 		var ret;
-		
+
 		if (prop == "opacity" && jQuery.browser.msie)
 			return jQuery.attr(elem.style, "opacity");
-			
+		
 		if (prop == "float" || prop == "cssFloat")
-		    prop = jQuery.browser.msie ? "styleFloat" : "cssFloat";
+			prop = jQuery.browser.msie ? "styleFloat" : "cssFloat";
 
 		if (!force && elem.style[prop])
 			ret = elem.style[prop];
@@ -1431,10 +1431,8 @@ jQuery.extend({
 				});
 
 		} else if (elem.currentStyle) {
-
 			var newProp = prop.replace(/\-(\w)/g,function(m,c){return c.toUpperCase();});
 			ret = elem.currentStyle[prop] || elem.currentStyle[newProp];
-			
 		}
 
 		return ret;
@@ -1527,18 +1525,20 @@ jQuery.extend({
 		};
 		
 		// IE actually uses filters for opacity ... elem is actually elem.style
-		if ( name == "opacity" && jQuery.browser.msie && value != undefined ) {
-			// IE has trouble with opacity if it does not have layout
-			// Force it by setting the zoom level
-			elem.zoom = 1; 
+		if ( name == "opacity" && jQuery.browser.msie ) {
+			if ( value != undefined ) {
+				// IE has trouble with opacity if it does not have layout
+				// Force it by setting the zoom level
+				elem.zoom = 1; 
 
-			// Set the alpha filter to set the opacity
-			return elem.filter = elem.filter.replace(/alpha\([^\)]*\)/gi,"") +
-				( value == 1 ? "" : "alpha(opacity=" + value * 100 + ")" );
+				// Set the alpha filter to set the opacity
+				elem.filter = (elem.filter || "").replace(/alpha\([^)]*\)/,"") +
+					(parseFloat(value).toString() == "NaN" ? "" : "alpha(opacity=" + value * 100 + ")");
+			}
 
-		} else if ( name == "opacity" && jQuery.browser.msie )
 			return elem.filter ? 
-				parseFloat( elem.filter.match(/alpha\(opacity=(.*)\)/)[1] ) / 100 : 1;
+				(parseFloat( elem.filter.match(/opacity=([^)]*)/)[1] ) / 100).toString() : "";
+		}
 		
 		// Certain attributes only work when accessed via the old DOM 0 way
 		if ( fix[name] ) {
