if (document.images) {
            img1on = new Image();
            img1on.src = "images/nav/home_on.gif";
            img2on = new Image();
            img2on.src = "images/nav/about_on.gif";
            img3on = new Image();
            img3on.src = "images/nav/tech_on.gif";
            img4on = new Image();
            img4on.src = "images/nav/clients_on.gif";
            img5on = new Image();
            img5on.src = "images/nav/contact_on.gif";

                               
            img1off = new Image();
            img1off.src = "images/nav/home_off.gif";
            img2off = new Image();
            img2off.src = "images/nav/about_off.gif";
            img3off = new Image();
            img3off.src = "images/nav/tech_off.gif";
            img4off = new Image();
            img4off.src = "images/nav/clients_off.gif";
            img5off = new Image();
            img5off.src = "images/nav/contact_off.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");
        }

}