if (document.images) {

img1on = new Image();           // On images
img1on.src = "/graphics/nav-nmmainstreet-on.gif";
img2on = new Image();
img2on.src = "/graphics/nav-friends-on.gif";
img3on = new Image();
img3on.src = "/graphics/nav-toolbox-on.gif";
img4on = new Image();
img4on.src = "/graphics/nav-coalition-on.gif";


img1off = new Image();          // Off images
img1off.src = "/graphics/nav-nmmainstreet.gif";
img2off = new Image();
img2off.src = "/graphics/nav-friends.gif";
img3off = new Image();
img3off.src = "/graphics/nav-toolbox.gif";
img4off = new Image();
img4off.src = "/graphics/nav-coalition.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");
        }
}