var state = 'hidden';
var newZ1;
var newZ2;

function showHide(id1, id2) {
    if (state == 'visible') {
        state = 'hidden';
        newZ1 = 1;
        newZ2 = 1;
    }
    else {
        state = 'visible';
        newZ1 = 91;
        newZ2 = 90;
    }

    if (document.all) { //IS IE 4 or 5 (or 6 beta)
        eval( "document.all." + id1 + ".style.visibility = state");
        eval( "document.all." + id2 + ".style.visibility = state");
        eval( "document.all." + id1 + ".style.zIndex = newZ1");
        eval( "document.all." + id2 + ".style.zIndex = newZ2");
    }

    if (document.layers) { //IS NETSCAPE 4 or below
        document.layers[id1].visibility = state;
        document.layers[id2].visibility = state;
        document.layers[id1].zIndex = newZ1;
        document.layers[id2].zIndex = newZ2;
    }

    if (document.getElementById && !document.all) {
        elem1 = document.getElementById(id1);
        elem2 = document.getElementById(id2);
        elem1.style.visibility = state;
        elem2.style.visibility = state;
        elem1.style.zIndex = newZ1;
        elem2.style.zIndex = newZ2;
    }
}