The free version of SQL Server 2005 is the “Express” edition. Its a cut down
version of SQL Server 2005 and is ideal as an upgrade from Access, for desktop
use or small multi-user databases. Its not designed for large scale production
use, and comes with a number of limitations. The most notable limitations are:

SQL Server 2005 Express Edition Limitations
RAMMaximum 1 GB
Database SizeMaximum 4 GB
Operating SystemsWindows Server 2003 SP1 / 2000 SP4 / XP SP2 / Vista (Requires SQL Server 2005 SP2)

While Express edition will install on a machine with multiple CPUs and
more than 1GB of RAM it will not use the additional hardware. To increase
the performance of express through additional CPUs and RAM you need to
upgrade to Workstation, Standard or Enterprise edition.

Additional features of SQL Server 2005 that are limited or not available in
the Express edition:

SQL Server 2005 Express Edition
Full Text SearchOnly in
Express Advanced Services
Reporting ServicesOnly in
Express Advanced Services
Management Studio

Only in
Express Advanced Services

SQL Server Integration Services (SSIS)No
Partitioned TablesNo
Indexed ViewsNo
Database MirroringNo
Database Tuning AdvisorNo
SQL Agent Job SchedulingNo
Notification ServicesNo
Web Services (HTTP Endpoints)No
Service BrokerMay be a Client only
Transational ReplicationMay be a Subscriber only
Merge ReplicationMay be a Subscriber only

More information on

Microsoft SQL Server 2005 Express Edition
can be found in the

product page

For a full list of

SQL Server 2005 Express Features

See how Express compares to other versions of SQL Server 2005

See how the Express and Express Advanced Services compare