The IIS Version Manager includes a COM interface that provides information about installed IIS versions and the managed Microsoft.Web.Diagnostics namespace that contains error and diagnostics information about IIS Express failures.
IIS Express is a lightweight, self-contained version of IIS that is optimized for developers. IIS Express makes it easy to use the most current version of IIS to develop and test websites. It has all the core capabilities of IIS 7 as well as additional features designed to ease website development. For more information, see IIS Express Overview