if (document.images) {
                          
            img1on = new Image();                                       // Active Images
            img1on.src = "http://www.psiparts.com/images/btn_products_on.gif";        
            img2on = new Image();
            img2on.src = "http://www.psiparts.com/images/btn_compinfo_on.gif";
            img3on = new Image();
            img3on.src = "http://www.psiparts.com/images/btn_markinfo_on.gif";
            img4on = new Image();
            img4on.src = "http://www.psiparts.com/images/btn_career_on.gif";
            img5on = new Image();
            img5on.src = "http://www.psiparts.com/images/btn_contact_on.gif";
            img6on = new Image();
            img6on.src = "http://www.psiparts.com/images/btn_help_on.gif";

                                                           
            img1off = new Image();                                      // inactive Images
            img1off.src = "http://www.psiparts.com/images/btn_products.gif";  
            img2off = new Image();
            img2off.src = "http://www.psiparts.com/images/btn_compinfo.gif";
            img3off = new Image();
            img3off.src = "http://www.psiparts.com/images/btn_markinfo.gif";
            img4off = new Image();
            img4off.src = "http://www.psiparts.com/images/btn_career.gif";
            img5off = new Image();
            img5off.src = "http://www.psiparts.com/images/btn_contact.gif";
            img6off = new Image();
            img6off.src = "http://www.psiparts.com/images/btn_help.gif";
            
        }

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

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