<reference name="root">
<?php
$coupon = Mage::getSingleton('checkout/session')->getQuote()->getCouponCode();
if(($coupon == "SE50") || ($coupon == "SE00")) {
?>
<action method="setTemplate"><template>page/2columns-right.phtml</template></action>
<?php } else { ?>
<action method="setTemplate"><template>page/checkout-onepage.phtml</template></action>
<?php } ?>
</reference>

var data = jQuery('#product_addtocart_form').serialize();
data += '&isAjax=1';
jQuery('#preloader .loader').fadeIn(300);
try {
jQuery.ajax({
url: url,
dataType: 'json',
type: 'post',
data: data,
success: function (data) {
showMessage(data);
if(data.status != 'ERROR'){
ajax_add_to_cart_post_update(data);
/*code added*/
window.location.href = checkout;
/*code added*/
}
}
});
} catch (e) {
}