[Freeware] This authoring tool can create Windows Installer Packages.

The Microsoft® Windows® Software Development Kit (SDK) provides the documentation, samples, header files, libraries, and tools you need to develop applications that run on Windows. The applications you develop with the latest edition of the SDK (Windows® Server 2003 R2 Platform) can run on the x86, x64 and Itanium-based versions of Windows Server 2003, Windows Server 2003 R2, Windows XP SP2, Windows XP x64 Pro Edition, and Windows 2000.

ORCA is a Microsoft utility for modifying and validating Windows Installer packages. It is a database tool intended for setup authors and administrators that works with the Windows Installer Service. This utility is a part of the Windows Installer SDK download along with other MSI related tools. You can use Orca to open and modify MSI packages and ISM project files. Note: Because Orca allows for direct modification of the MSI package or ISM, ISE files, which may have an impact on the project, it is recommended that users make a backup copy of the file they are about to modify.

Visit the SDK Platform Site page to download the Windows Installer SDK. Visit the MSDN pages for ORCA to know more about the tool. If you are planning to develop Windows Installer Packages with SDK platform, you must know Windows Installer Development Tools (that includes ORCA) provided with the install of SDK.