fullscreen background image CSS3 Technik;

http://css-tricks.com/perfect-full-page-background-image/

geht in jedem css3-ready browser (IE9 auch)

html {
background: url(full.jpg) no-repeat center center fixed;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}