Get customer data by selecting the particular field in magento

Get customer data by selecting the particular field in magento 

$collection = Mage::getModel('customer/customer')->getCollection();
    //$Collection->addFieldToSelect('email');
    $collection->getSelect()
    ->reset(Zend_Db_Select::COLUMNS)
    ->columns('email as cust_email')
    ->columns('created_at as create_time');
    echo '<pre>';
    print_r($collection->getData());