[From Microsoft TechNet]
SQL Server 2005 is an ideal database platform for use in shared and dedicated Web hosting environments. This paper provides best practices for configuring SQL Server 2005 to optimize security, tenant isolation, and the performance of your hosted SQL Server 2005 deployment. Sample scripts for provisioning users and databases for use in shared hosting are included.
The article continues at
http://www.microsoft.com/technet/prodtechnol/sql/bestpractice/SQL2005DGWHE.mspx