if(document.images) {
    img1 = new Image(); img1.src = "images/nav_about_red.gif";
    img2 = new Image(); img2.src = "images/nav_whoswho_red.gif";
    img3 = new Image(); img3.src = "images/nav_contact_red.gif";
    img4 = new Image(); img4.src = "images/nav_tickets_red.gif";
    img5 = new Image(); img5.src = "images/nav_myspace_red.gif";
    img6 = new Image(); img6.src = "images/nav_fringe_red.gif";
}

function replaceImg(imgName, imgFileName)
{
    if(document.images)
        document.images[imgName].src = "images/" + imgFileName;
}