.ad1
{
    position: fixed;
    _position:absolute;
    width: 150px;
    height: 60px;
    top: 270px;
    left: 0;
    z-index:1000;
}
.ad2
{
    position: fixed;
    _position:absolute;
    width: 150px;
    height: 60px;
    top: 270px;
    right: 0;
    z-index:1000;
}
img
{
    border: 0;
}