The Web Platform Installer (Web PI) is a simple free tool that allows you to install all or part of Microsoft's entire Web Platform and keep each individual component up-to-date. Web PI has now hit the final 1.0 version (under 60KB). Just like the RC, the final version has three installation options:

Complete: installs all available server and development products, Web server components, Web server extensions, and additional technologies
ASP.NET Developer: installs the server components, tools and technologies that support the development and hosting of ASP.NET applications
Custom: allows you to choose exactly which components are installed

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