Thanks Thomas. "This production quality supported release of MSXML 4.0 offers a number of new features and improvements over the MSXML 3.0, including support for the XML Schema language; substantially faster parser and XSLT engine; better support for streamed XML processing; improved conformance; and bug fixes. MSXML 4.0 is not a complete replacement for MSXML 3.0, because some obsolete and non-conformant features are no longer supported. MSXML 4.0 installs side by side with MSXML 3.0 and earlier, without any interference. " 4.8 MB.

Note: Upgrade from beta 4.0 releases to RTM is not supported. You have to uninstall all technology preview releases from your computer prior to installing the MSXML 4.0 RTM version. You might have to delete msxml4*.dll files in your system (system32) directory manually.

Important note: MSXML 4.0 does not have version-independent ProgIDs. That means that if you had the April technology preview of MSXML 4.0, you will also have to unregister existing msxml4.dll, uninstall/remove it, and reregister MSXML 3.0. When you have completed these steps, you can proceed with the installation of MSXML 4.0 RTM. Otherwise a number of ProgIDs used by other applications (for example, the setup of Visual Studio.Net) will become unavailable. To unregister MSXML 4.0 and register MSXML 3.0, use the following commands: