<!-- menu pre load -->
function imgPreload()
{
	(new Image()).src = "Images/Companyprofile.png";
	(new Image()).src = "Images/Companyprofile_over.png";
	(new Image()).src = "Images/Service.png";
	(new Image()).src = "Images/Service_over.png";
	(new Image()).src = "Images/Recruitinfo.png";
	(new Image()).src = "Images/Recruitinfo_over.png";
	(new Image()).src = "Images/Contactus.png";
	(new Image()).src = "Images/Contactus_over.png";
}
window.onload = function(){ 
            if(!window.addEventListener)
            {
                document.getElementById('menu1').attachEvent("onmouseover",function(){document.getElementById('menu1').src = "Images/Companyprofile_over.png";});
                document.getElementById('menu1').attachEvent("onmouseout",function(){document.getElementById('menu1').src = "Images/Companyprofile.png";});
                document.getElementById('menu2').attachEvent("onmouseover",function(){document.getElementById('menu2').src = "Images/Service_over.png";});
                document.getElementById('menu2').attachEvent("onmouseout",function(){document.getElementById('menu2').src = "Images/Service.png";});
                document.getElementById('menu3').attachEvent("onmouseover",function(){document.getElementById('menu3').src = "Images/Recruitinfo_over.png";});
                document.getElementById('menu3').attachEvent("onmouseout",function(){document.getElementById('menu3').src = "Images/Recruitinfo.png";});
                document.getElementById('menu4').attachEvent("onmouseover",function(){document.getElementById('menu4').src = "Images/Contactus_over.png";});
                document.getElementById('menu4').attachEvent("onmouseout",function(){document.getElementById('menu4').src = "Images/Contactus.png";});
            }
	    else
	    {
                document.getElementById('menu1').addEventListener("mouseover",function(){document.getElementById('menu1').src = "Images/Companyprofile_over.png";},false);
                document.getElementById('menu1').addEventListener("mouseout",function(){document.getElementById('menu1').src = "Images/Companyprofile.png";},false);
                document.getElementById('menu2').addEventListener("mouseover",function(){document.getElementById('menu2').src = "Images/Service_over.png";},false);
                document.getElementById('menu2').addEventListener("mouseout",function(){document.getElementById('menu2').src = "Images/Service.png";},false);
                document.getElementById('menu3').addEventListener("mouseover",function(){document.getElementById('menu3').src = "Images/Recruitinfo_over.png";},false);
                document.getElementById('menu3').addEventListener("mouseout",function(){document.getElementById('menu3').src = "Images/Recruitinfo.png";},false);
                document.getElementById('menu4').addEventListener("mouseover",function(){document.getElementById('menu4').src = "Images/Contactus_over.png";},false);
                document.getElementById('menu4').addEventListener("mouseout",function(){document.getElementById('menu4').src = "Images/Contactus.png";},false);
	    }
}

<!-- service -->
function openWindow(index)
{
	var name = '';

	if (index == 1)
	{
		name = './devWeb.html';
	}
	else if (index == 2)
	{
		name = './devEmbedded.html';
	}
	else if (index == 3)
	{
		name = './devOpen.html';
	}

	if (name != '')
	{
		window.open(name, '', '');
	}
}