Automatically Create Wordpress User From UltraCart Purchase

Need a script that will automatically create a Wordpress user account when a product is purchased from my Ultracart shopping cart. ? The username will be the customer's email address. ? The user account will be created in the 'Bronze Member' Role. Here is how it should work: 1. customer purchases a product and Ultracart will process the credit card 2. if the credit card is processed without errors, then? an account is created in Wordpress using the customer's email address. 3. the account should be in the 'Bronze Member' Role