if (document.images) {
    aboutusoff = new Image();
    aboutusoff.src = "/img/nav/aboutus_off.gif";
    servicesoff = new Image();
    servicesoff.src = "/img/nav/services_off.gif";
    portfoliooff = new Image();
    portfoliooff.src = "/img/nav/portfolio_off.gif";
    clientlistoff = new Image();
    clientlistoff.src = "/img/nav/clientlist_off.gif";
    contactusoff = new Image();
    contactusoff.src = "/img/nav/contactus_off.gif";

    aboutuson = new Image();
    aboutuson.src = "/img/nav/aboutus_on.gif";
    serviceson = new Image();
    serviceson.src = "/img/nav/services_on.gif";
    portfolioon = new Image();
    portfolioon.src = "/img/nav/portfolio_on.gif";
    clientliston = new Image();
    clientliston.src = "/img/nav/clientlist_on.gif";
    contactuson = new Image();
    contactuson.src = "/img/nav/contactus_on.gif";
}

// Function to 'activate' images.

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

// Function to 'deactivate' images.

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

// Function to create dynamic pop up window, currently set to center window on screen.

function newWindow(url, name, wid, hgt, scr, res, stat, loc, mnu, tool, x, y) {
    if (screen) {
        widthOfScreen = screen.width;
        heightOfScreen = screen.height;
    }
    midX = widthOfScreen / 2;
    midY = heightOfScreen / 2;
    midWid = wid / 2;
    midHgt = hgt / 2;
    x = midX - midWid;
    y = midY - midHgt;
    windowOpts = "width=" + wid + ",height=" + hgt + ",scrollbars=" + scr + ",resizable=" + res + ",status=" + stat + ",location=" + loc + ",menubar=" + mnu + ",toolbar=" + tool + ",left=" + x + ",top=" + y;
    popUpWindow = window.open(url, name, windowOpts);
}