Download SQL Server 2008 Express with Tools/SQL Server 2008 Express Advanced Series.
Run the SQLEXPRADV_x86_ENU.exe file.
Click the System Configuration Checker in the SQL Server Installation Center to see if all the prerequisites are installed.
Choose Installation.
Type the product key and click Next.
The product key setting page appears.
Accept the licence terms and click Next.
The licence terms page appears.
Click Install in the Set Up Support Files screen. Click Next on completing the setup.
In the Features Selection screen that appears, select the Database Engine Services and ManagementTools-Basic features.
Type MSSQLSERVER in the Named instance and Instance ID boxes for Instance configuration. Click Next.
See http://msdn.microsoft.com/en-us/library/ms165614.aspxfor more information about configuration.
Make the following changes in the Server Configuration page
Use NT AUTHORITY\SYSTEM as the account name for SQL Server Database engine.
Change the SQL Server browser startup to Automatic.
Other settings remain the same.
Do the following changes in the Database Engine Configuration screen: