Karni Retail Installer
Karni Retail Installation Instruction
SQL Server Installer
SQL Server Installation Instruction
SQL Server 2008 SP1 Installer For Vista
before installing it your system must have either Windows XP SP3 or Windows 7 or Windows 2008 with .NET Framwork 3.5 SP1.
For more inatallation option please visit installation of SQL2008
Due to security reason all installer packages are in Zip (Compressed) format. So after download first extract them. After extracting you will get an executable program.