#gallery1 {position:absolute; width: 350px;
margin-left: auto;
margin-right: auto;
margin-top: 5px; 
height: 425px;
}

#thumbs1 {width:350px; float:left;}
#thumbs1 a {display:block; float:left; margin:0 0 5px 5px; width:75px; height:75px; border:1px solid #000;}
#thumbs1 a img {width:75px; height:75px; border:0;}
#thumbs1 a:hover {border-color:#ddd;}
#thumbs1 a:hover img {position:absolute; width:auto; height:auto; left:105%; top:5px; border:1px solid #333;}

#thumbs2 {width:350px; float:left;}
#thumbs2 a {display:block; float:left; margin:0 0 5px 5px; width:75px; height:75px; border:1px solid #000;}
#thumbs2 a img {width:75px; height:75px; border:0;}
#thumbs2 a:hover {border-color:#ddd;}
#thumbs2 a:hover img {position:absolute; width:auto; height:auto; left:105%; top:-105px; border:1px solid #333;}

#thumbs3 {width:350px; float:left;}
#thumbs3 a {display:block; float:left; margin:0 0 5px 5px; width:75px; height:75px; border:1px solid #000;}
#thumbs3 a img {width:75px; height:75px; border:0;}
#thumbs3 a:hover {border-color:#ddd;}
#thumbs3 a:hover img {position:absolute; width:auto; height:auto; left:105%; top:-205px; border:1px solid #333;}