Application development using Microsoft SQL Server 2000 discusses several key enhancements in SQL Server 2000 including application migration assistance, engine enhancements like user-defined functions and triggers, XML support, and the ability to run multiple SQL Server instances on a single machine. The document provides examples of cascading deletes and updates, scalar and table-valued user-defined functions, instead-of triggers, indexes on computed columns and views, and different options for generating XML output from SQL queries. It also lists additional resources for more information.