The ArcView setup was created using Microsoft Windows Installer technology. This technology uses a package file (.msi) and a client-side installer service (msiexec.exe). The Windows Installer is a service that runs on your operating system. This service enables the operating system to manage the installation and uses the information contained within the package file to install the software.
The Msiexec.exe program is a component of Windows Installer. Msiexec.exe uses a dynamic link library, Msi.dll, to read the package files (.msi), apply transforms (.mst), and incorporate command-line options.
More information on Windows Installer can be found in the Windows Installer Software Development Kit (SDK).
http://www.microsoft.com/msdownload/platformSDK/sdkupdate/
The setup.msi installer package can be used to deploy ArcView in Windows Installer supported environments such as Active Directory and Microsoft System Management Server. See Installing ArcView silently for information on command line options for installing ArcView. A deployment white paper is available on the ESRI Support Center, a link to White Papers can be found in the Knowledge Base page.