Do you need that width/height since the image you linked to is only 1279 x 1554 pixels? If not, just make the size the same as the background image:
selector_name {
width: 1279px; min-height: 1554px;
margin: 0 auto;
background: url((img/bg.jpg) no-repeat center scroll;
}
Or, use CSS3 rules:
selector_name {
background: url(bgimage.jpg) no-repeat center scroll;
background-size: 100%;
}
For Firefox 3.6 (-moz-background-size) and Opera 10.0 (-o-background-size).
More info here.