AJAX Troubles

Okay, so I’ve posted this problem a few times now, updating it as I try new things and get closer, but I know I’m really close now, just need a bit of your AJAX expertise. Anyway, the background: I am trying to update a custom user profile field from a page on the site (in this case, I am storing the user’s experience in a rpg-type game) but no matter what I do it doesn’t seem to want to update the meta. So, here’s the code for my custom user field, in case you need to reference it:

add_action( 'show_user_profile', 'my_show_extra_profile_fields' );
add_action( 'edit_user_profile', 'my_show_extra_profile_fields' );

function my_show_extra_profile_fields( $user ) { ?>

	<h3>Extra profile information</h3>

	<table class="form-table">
		<tr>
			<th><label for="experience">Total Experience</label></th>
			<td>
				<input type="text" name="experience" id="experience" value="<?php echo esc_attr( get_the_author_meta( 'experience', $user->ID ) ); ?>" class="regular-text" /><br />
				<span class="description">Your Total Experience</span>
			</td>
		</tr>
	</table>
<?php }

add_action( 'personal_options_update', 'my_save_extra_profile_fields' );
add_action( 'edit_user_profile_update', 'my_save_extra_profile_fields' );
function my_save_extra_profile_fields( $user_id ) {
	if ( !current_user_can( 'edit_user', $user_id ) )
		return false;
	update_user_meta( $user_id, 'experience', $_POST['experience'] );
}

Here is my form that I am using to update the experience:

<form id="yourprofile" action="" method="post">
<p>
<input type="text" name="checkuser_id" id="checkuser_id" value="<?php global $current_user; get_currentuserinfo(); echo $current_user->ID; ?>" />
</p>
<div style="clear: both;">
<h4>Total Experience</h4>
<?php if ( get_the_author_meta( 'experience' ) ) { ?>
<input name="userxp" id="userxp" value="<?php the_author_meta( 'experience' ); ?>" type="text" readonly>
<?php } // End check for experience ?>
</div>
<input name="updatexp" id="updatexp" class="btnb" type="submit" value="Update Experience">
</form>

here is the javascript I added to the page as well:

<script type="text/javascript">
jQuery(document).ready(function(){
	var userid = jQuery('#checkuser_id').val();
	var exp = jQuery('#userxp').val();
	jQuery("#yourprofile").submit(function()	{
				var data = {
					action: 'my_save_userxp',
					userxp: exp,
					checkuser_id: userid
				};
				jQuery.post("<?php echo admin_url('admin-ajax.php'); ?>", data,
				function(response){
					alert('Got this from the server: ' + response)
				});
	});
});
</script>

and here is what I added to functions.php:

add_action('wp_ajax_my_save_userxp', 'my_save_userxp_callback');
function my_save_userxp_callback() {
$user_id = $_POST['checkuser_id'];
$userxp = $_POST['userxp'];
global $wpdb;
update_user_meta( $user_id, 'experience', $userxp );
}

Please, I am begging anyone there with ajax knowledge to give me any pointers. I am really at a dead end here and can’t continue with my project until I get this up and running. Thanks all in advance, hope to hear from you soon