Migration tool: http://litextension.com/shopping-cart-migration/interspire-to-magento.html
Interspire to Magento Migration Tool allows you to migrate Products, Customers, Passwords, Orders, Categories and Other Data within only 3 simple steps.

Interspire to Magento supports to maintain all old url links of products and categories when you plan to replace the Loaded Ecommerce store, thus helps keeping your current SEO ranking you have built up for years. :)