Enqueuing jquery.min.js

Alright, I know this should be simple but I am obviously looking over something. I am hoping someone can chime in with some help. I am trying to enqueue the Google JQuery lib and I just cant get it right to save me.

Here is what I have, I have tried to deregister the jquery script and every other form/variation but just cant get it. I’m sure this has been answered thousands of times. Please be patient 😀 Thanks

function wilmper_load_js_lib() {

wp_deregister_script('jquery');

wp_register_script( 'jquery', 'http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js', array('jquery'));

wp_enqueue_script( 'jquery' );
}
add_action( 'wp_enqueue_scripts', 'wilmper_load_js_lib' );

Please tell me where/what went wrong, thanks in advance!