Be sure to check these out:
White Paper: Security Overview for Database Administrators 2008.
SQL Server 2008 is secure by design, default, and deployment. Microsoft is committed to communicating information about threats, countermeasures, and security enhancements as necessary to keep your data as secure as possible. This paper covers some of the most important security features in SQL Server 2008. It tells you how, as an administrator, you can install SQL Server securely and keep it that way, even as applications and users make use of the data stored within.
White Paper: SQL Server 2008 Compared to Oracle Database 11g
Microsoft SQL Server has steadily gained ground on other database systems and now surpasses the competition in terms of performance, scalability, security, developer productivity, business intelligence (BI), and compatibility with the 2007 Microsoft Office System. It achieves this at a considerably lower cost than does Oracle Database 11g.
White Paper: Running SQL Server 2008 on Windows Server 2008
The combination of SQL Server 2008 and Windows Server 2008 offers enterprise IT administrators and professional developers a superlative platform for mission-critical applications together with enhanced end-to-end security, management, and development capabilities.