De Valdez

This will be cut and dry. Drag and drop. Show this to a client, and they will be happier. Guaranteed.

This changes the WP Logo to an image of your choosing, and alters the link and title of that node.

Smiles all around.

//Custom Login Screen
function custom_login_logo() {
    echo '<style type="text/css">
        		h1 a {
				background:url('.get_bloginfo('template_directory').'/images/sprite.png) no-repeat scroll -149px -73px;
				height: 8px !important;
				margin: 10px auto;
				width: 213px !important;
			}
    </style>';
}

function change_wp_login_url() {
echo bloginfo('url');
}
function change_wp_login_title() {
echo get_option('blogname');
}
add_action('login_head', 'custom_login_logo');
add_filter('login_headerurl', 'change_wp_login_url');
add_filter('login_headertitle', 'change_wp_login_title');