Live Example: JSFiddle
The Accepted answer has some problem. The image wasn't resized there. Use background-size property for resizing the image.
HTML:
<div id="image"></div>
CSS:
#image {
background-image: url('image1');
background-size: 300px 390px;
width: 300px;
height:390px;
}
#image:hover{
background: url("image2");
background-size: 300px 390px;
}