#images {
  position:absolute;
  top: 50%;
  left: 50%;
  width:488px;
  height:338px;
  margin-top: -169px; /*set to a negative number 1/2 of your height*/
  margin-left: -244px; /*set to a negative number 1/2 of your width*/
}

.image1 {
   width:488px;
   height:129px;
   background:url(img/wanderersx_bw.jpg);
}

.image1 a{
   display:block;
   width:488px;
   height:129px;
   background:url(img/wanderersx_bw.jpg);
}

.image1 a:hover {
   display:block;
   width:488px;
   height:129px;
   background:url(img/wanderersx.jpg);
}

.image2 {
    margin-top: 80px;
    width:488px;
    height:129px;
    background:url(img/visitorsj_bw.jpg);
}

.image2 a{
    display:block;
    width:488px;
    height:129px;
    background:url(img/visitorsj_bw.jpg);
}

.image2 a:hover{
    width:488px;
    height:129px;
    background:url(img/visitorsj.jpg);
}