a img#hover1 { 
overflow: hidden; 
width: 203px; 
height: 91px; 
background-image: url(button1a.jpg);
}

a:hover img#hover1 { 
overflow: hidden; 
width: 203px; 
height: 91px; 
background-image: url(button1b.jpg);
}

a img#hover2 { 
overflow: hidden; 
width: 203px; 
height: 79px; 
background-image: url(button1a.jpg);
}

a:hover img#hover2 { 
overflow: hidden; 
width: 203px; 
height: 79px;
background-image: url(button1b.jpg);
}

a img#hover3 { 
overflow: hidden; 
width: 203px; 
height: 73px; 
background-image: url(button1a.jpg);
}

a:hover img#hover3 { 
overflow: hidden; 
width: 203px; 
height: 73px;
background-image: url(button1b.jpg);
}