Abstract: We present a new cooperative user interface for e-shopping in B2C e-commerce. COSIMA is a smart and animated Internet avatar with synchronized dynamic voice output who assists customers through their e-shopping tours and advises them in the spirit of a real salesperson in the old economy. COSIMA benefits from a Preference SQL-based search engine that relies on the Pareto-principle, computing best matching results to the customer's wishes. This enables COSIMA to offer ideal hits or suitable alternatives with one single query, to value these search results in terms of the stated preferences and to generate proper voice output following basic principles of sales psychology. As a sample application we present our meta-search engine for comparison shopping. Since COSIMA constitutes an entire technological framework, it can easily be adjusted to other e-commerce environments by customizing the search engine, the avatar animations and the speech contexts.