blog = new Image();
blog.src = "homepage/blog.jpg";

collection = new Image();
collection.src = "homepage/collection.jpg";

$(document).ready(function() {
    $('#collectionLink a').hover(function() {
        $('#container').css('background-image','url(homepage/collection.jpg)');
    });
    $('#blogLink a').hover(function() {
        $('#container').css('background-image','url(homepage/blog.jpg)');
    });
});