.search-button{
    border: none;
    padding: 0;
    display: block;
    float: left;
    width: 120px;
    height: 30px;
    text-transform: uppercase;
    text-indent: -9000px;
    cursor: pointer;
    background: url(search-button.gif) no-repeat 0 0;
}

.search-button:hover{
    background: url(search-button.gif) no-repeat 0 -30px;
}