if (document.images)
    {
    button1on= new Image();
    button1on.src="images/aboutus_in.gif";
    button1off= new Image();
    button1off.src="images/aboutus_out.gif";
    button2on= new Image();
    button2on.src="images/services_in.gif";
    button2off= new Image();
    button2off.src="images/services_out.gif";
    button3on= new Image();
    button3on.src="images/support_in.gif";
    button3off= new Image();
    button3off.src="images/support_out.gif";
    button4on= new Image();
    button4on.src="images/partners_in.gif";
    button4off= new Image();
    button4off.src="images/partners_out.gif";
    button5on= new Image();
    button5on.src="images/contactus_in.gif";
    button5off= new Image();
    button5off.src="images/contactus_out.gif";
    }

function lightup(imgName)
    {
    if (document.images)
        {
            imgOn=eval(imgName + "on.src");
            document[imgName].src= imgOn;
        }
    }

function turnoff(imgName)
    {
    if (document.images)
        {
            imgOff=eval(imgName + "off.src");
            document[imgName].src= imgOff;
        }
    }