Contributed By: Cliff Hobbs [MVP ConfigMgr]
During the upgrade process of any Site with the SMS version of the Inventory Tool for Microsoft Updates (ITMU) installed, the ConfigMgr Setup process automatically attempts to upgrade the SMS version of ITMU to the ConfigMgr version.

Part of this upgrade involves either downloading the ConfigMgr version of the Microsoft Updates Catalog (“wsusscn2.cab”), directly from the Internet or by pointing the setup process to a copy of the file previously downloaded manually.

If your Central Site doesn't have any direct Internet connectivity, the “wsusscn2.cab” needs to be downloaded manually and placed on the Central Site in a location that can be referenced during the upgrade to ConfigMgr.

To manually download the latest version of the “wsusscn2.cab” file goto:

http://go.microsoft.com/fwlink/?LinkId=74689

NOTE: The download is approxiamtely 22 MB