Abstract (THX TO edhild: his second post is a great post)
The scenario is a common one: An organization has some LOB application that is critical to their everyday needs. In fact users find themselves logging in periodically just to check one particular screen of information. Often, this information is summary data within the system. This article will detail a solution to build a web part that pulls this information into the corporate portal increasing user productivity by giving them access outside of an otherwise siloed application. In this example, the summary data is equally available for all users; therefore the web part will impersonate a specific windows account that has been granted access to the data. The solution will accomplish this using SharePoint Portal Server's single sign-on service.

To fulfill the above scenario, the solution will execute the "Ten Most Expensive Products" stored procedure from the Northwind datbase using a specific windows credential for all users and display the results in a SPS web part.

Read all on: http://blogs.msdn.com/edhild/articles/377362.aspx