Oracle 10g Express Edition is the next version of MSDE and is a free, easy-to-use, lightweight, and embeddable version of SQL Server 2005.
Free to download, free to redistribute, free to embed, and easy for new developers to use immediately.
SQL Server Express includes powerful features such as SQL Server 2005 Reporting Services, for creating and delivering traditional and interactive reports.
It als includes a powerful graphical management tool, SQL Server 2005 Management Studio Express, for easily managing your database.
Best of all, as your needs grow, your applications will seamlessly work with the rest of the SQL Server product family.