Enterprise Data Management
High Availability – Failover clustering and database mirroring technology in SQL Server 2005 will enable enterprises to deliver highly reliable, available applications to employees, customers, and partners.
Management Tools – SQL Server 2005 introduces an integrated suite of management tools and management application programming interfaces (APIs) to provide ease of use, manageability, and support for operating large-scale SQL Server deployments.
Security Enhancements – SQL Server 2005 has been designed to help provide the highest level of security for enterprise data through features such as database encryption, more secure default settings, password policy enforcement, granular permissions control, and an enhanced security model.
Scalability – Scalability advancements in SQL Server 2005 include table partitioning, replication enhancements, and 64-bit support.

Developer Productivity
Common Language Runtime (CLR) Integration – SQL Server 2005 introduces the capability to develop database objects using any Microsoft .NET language.
Deep XML Integration – SQL Server 2005 delivers a new XML data type, enabling the storage of XML fragments or documents in SQL Server databases.
Transact-SQL Enhancements – New query types and the capability to use error handling in transactions provide developers with more flexibility and control in SQL Server query development.
SQL Service Broker – SQL Service Broker provides an innovative distributed asynchronous application framework for new levels of scalability.

Business Intelligence
Analysis Services – Analysis Services delivers extensions to the scalability, manageability, reliability, availability, and programmability of data warehousing, business intelligence, and line-of-business solutions.
Data Transformation Services (DTS) – A complete redesign of the DTS architecture and tools provides developers and database administrators with increased flexibility and manageability.
Reporting Services – Reporting Services is a new report server and tool set for building, managing, and deploying enterprise reports.
Data Mining – Data mining is enhanced with four new algorithms as well as improved data modeling and manipulation tools.