if (document.images)
   {
     pic1on= new Image(165,26);
     pic1on.src="images/overknop-algemeen.gif";  
     pic2on= new Image(165,29);
     pic2on.src="images/overknop-soorten-vloeren.gif"; 
     pic3on= new Image(165,49);
     pic3on.src="images/overknop-garantie.gif"; 
     pic4on= new Image(165,26);
     pic4on.src="images/overknop-prijzen.gif"; 
	 pic5on= new Image(165,42);
     pic5on.src="images/overknop-vragen-houten-vloeren.gif"; 
	 pic6on= new Image(165,27);
     pic6on.src="images/overknop-contact.gif"; 
	 pic7on= new Image(400,98);
     pic7on.src="images/contact-plank-over.jpg"; 

     pic1off= new Image(165,26);
     pic1off.src="images/knop-algemeen.gif";
     pic2off= new Image(165,29);
     pic2off.src="images/knop-soorten-vloeren.gif";
     pic3off= new Image(165,49);
     pic3off.src="images/knop-garantie.gif";
     pic4off= new Image(165,26);
     pic4off.src="images/knop-prijzen.gif";
	 pic5off= new Image(165,42);
     pic5off.src="images/knop-vragen-houten-vloeren.gif";
	 pic6off= new Image(165,27);
     pic6off.src="images/knop-contact.gif";
	 pic7off= new Image(400,98);
     pic7off.src="images/contact-plank.jpg";
   }

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;
    }
 }