if(document.all) {
layerRef = 'document.all("'; styleSwitch = '").style'; }
if (document.getElementById) {
layerRef = 'document.getElementById("'; styleSwitch = '").style'; }
if (document.layers) {
layerRef = 'document.layers["'; styleSwitch = '"]'; }

function ShowHide(id) {
    obj = document.getElementsByTagName("div");
    obj['linkNav2_1'].style.visibility = 'hidden';
    obj['linkNav2_2'].style.visibility = 'hidden';
    obj['linkNav2_3'].style.visibility = 'hidden';
    obj['linkNav2_4'].style.visibility = 'hidden';
    if (obj[id].style.visibility == 'visible') {
    obj[id].style.visibility = 'hidden';
    }
    else {
    obj[id].style.visibility = 'visible';
    }
}