[rousiland]

Looking at doing this as well and I would add that there are a lot of other tables that also need to be updated as they use the 'login' field as a key. As far as I can tell, the other tables that need updating are the ones listed below. You may also have additional tables from extra modules that also require an update.

xcart_change_password
xcart_customers
xcart_customer_bonuses
xcart_discount_coupons_login
xcart_login_history
xcart_old_passwords
xcart_orders
xcart_register_field_values
xcart_seller_addresses
xcart_stats_cart_funnel
xcart_stats_customers_products
xcart_subscription_customers
xcart_wishlist