In supportability, manageability, scalability, performance, interoperability, and business intelligence, SQL Server 2005 provides far richer 64-bit support than its predecessor. This paper describes these enhancements. Read the original paper here. Following abstract is taken from the same paper. Another interesting article on 64-bit Computing with SQL Server 2005 is here.
The primary differences between the 64-bit and 32-bit versions of SQL Server 2005 are derived from the benefits of the underlying 64-bit architecture. Some of these are:
Reference : Pinal Dave (http://blog.SQLAuthority.com)