The Developer's Assistant can be configured to use two main data sources, Microsoft Access or Microsoft SQL Server. The main difference is the library access times between the two data sources. The Developer's Assistant MS SQL data source is a little quicker when retrieving library contents. If you are using a Personal or Enterprise versions of MS SQL it is recommended to use the MS SQL data source. Depending on whether you purchased Professional or Enterprise determines which data source you are able to configure. Professional only uses MS Access while Enterprise allows for both MS Access and MS SQL.  To configure a Data Source, use Library - Configure Library Data Source...