http://www.manifold.net/doc/7x/sql_server_express_...
SQL Server Express Edition
The Manifold DVD includes a complete distribution of Microsoft® SQL Server™ 2005 Express Edition. SQL Server Express provides the power of SQL Server to Manifold System users at no additional charge.
Introduction
SQL Server 2005 Express Edition is derived from the same engine upon which Microsoft SQL Server 2005 is built. It is a newer and, in many key ways, better alternative to the SQL Server 2000 Desktop Engine (known as MSDE) distributed in earlier Manifold releases.
When delivered in SQL Server Express form, Microsoft has limited SQL Server in several ways:
§ A database cannot exceed 4 gigabytes in size.
§ SQL Server Express may be installed on a multiple CPU machine, but it will execute (run) only on a single processor or a single processor core if multi-core processors are used.
§ SQL Server Express may be installed on a server with any amount of memory, but will use only up to 1 GB of available RAM memory.
Other than these limitations SQL Server Express provides virtually the full power and breadth of SQL Server capabilities. Although MSDE was limited to no more than five users, SQL Server Express no longer has such an artificial throttle on performance. Within the limits of processor, RAM and maximum database size, SQL Server Express always runs at full speed.
SQL Server 2005 Features Comparison
http://www.microsoft.com/sql/prodinfo/features/com...
Note: If SQL Server 2005 Express is running on Windows XP Home, it is limited to five simultaneous connections. If it is running on Windows 2000 or Windows XP Professional, it is limited to 10 simultaneous connections. However, these are limitations of the operating system and not of SQL Server 2005 Express.
Upgrading MSDE 2000 to SQL Server 2005 Express
http://www.microsoft.com/technet/prodtechnol/sql/2...
MySQL Community Server
http://dev.mysql.com/downloads/mysql/5.0.html
dual license model: http://www.mysql.com/company/legal/licensing/faq.h...
MySQL Enterprise Basic $595