Link to VHD of SQL Server 2005 from Microsoft Downloads.
Microsoft SQL Server 2005 is comprehensive, integrated data management and analysis software that enables organizations to reliably manage mission-critical information and confidently run today’s increasingly complex business applications. By providing high availability and security enhancements as well as embedded reporting and data analysis tools, SQL Server 2005 allows companies to gain greater insight from their business information and achieve faster results for a competitive advantage. SQL Server 2005 is designed to integrate seamlessly with your other server infrastructure investments.