var agent = navigator.userAgent;
		var appver = navigator.appVersion;
		var nav = navigator.appName;
		var plf = null;
		var ver = null;
		if(agent.indexOf('Mac') != -1){
			plf = "Mac";
		}else if(agent.indexOf('Win') != -1){
			plf = "Win";
		}else{
			plf = "other";
		}
		if(agent.indexOf('MSIE') == -1){
			ver = appver.charAt(0);
			if(nav == "Netscape"){
				nav = "NN";
			}
		}else{
			ver = agent.charAt(agent.indexOf('MSIE') + 5);
			nav = "MSIE";
		}

		var imageDir = "images/";
        var loadList;
        var action = "off";
        function preLoad() {
                loadList = new Array("menu01_on.gif", "menu02_on.gif", "menu03_on.gif", "menu04_on.gif", "menu05_on.gif", "menu06_on.gif", "menu07_on.gif", "menu08_on.gif", "menu09_on.gif", "menu10_on.gif", "menu11_on.gif");
                onImages = new Array();
                for (field in loadList)
                {
                        onImages[field] = new Image();
                        onImages[field].src = imageDir + loadList[field];
                }
                action = "on";
        }
        function changeImage(fileName, imageName) 
        {
                if (action == "on") {
                        document.images[imageName].src = imageDir + fileName;
                }
        }