if (document.images) {

img1on = new Image();
img1on.src = "img/nav_home2.gif";
img1off = new Image();
img1off.src = "img/nav_home.gif";

img2on = new Image();
img2on.src = "img/nav_info2.gif";
img2off = new Image();
img2off.src = "img/nav_info.gif";

img3on = new Image();
img3on.src = "img/nav_leistungen2.gif";
img3off = new Image();
img3off.src = "img/nav_leistungen.gif";

img4on = new Image();
img4on.src = "img/nav_kontakt2.gif";
img4off = new Image();
img4off.src = "img/nav_kontakt.gif";

img5on = new Image();
img5on.src = "img/nav_impressum2.gif";
img5off = new Image();
img5off.src = "img/nav_impressum.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");}
}