How to migrate data from WP Ecommerce to Prestashop using LitExtension tool: http://litextension.com/prestashop-migration-tool/wp-ecommerce-to-prestashop.html
If you want to migrate all important data from shopping cart to Prestashop quickly, LitExtension Migration Tool is a good choice. Migration to Prestashop supports you to migrate products, categories, customers, password, orders, URL SEO ranking, custom field, taxes, reviews and other data from WPEC. Prestashop migration tool requires no technical knowledge.
