In troubleshooting an issue with the SBS user creation wizard, I wanted to know what was set as the default Organizational Unit in which users would be placed. Though the following works with any server version which is domain functional level Server 2003 or newer, SBS defaults to placing users in the MyBusiness\Users\SBSUsers OU and I wanted to verify this was set appropriately. There are 100 articles explaining how to change the default users OU using the command “Redirusr”, or “Redircmp” for computers, but it was difficult to find a link explaining how to locate the current defaults. There are a few links explaining where the information is stored, which is in the “wellKnownObjects” attribute of the properties of the domain, in Active Directory Users and Computers.
However when you click on “View”, to inspect the settings for that attribute, you get a popup warning; “There is no editor to handle this attribute”, and the same happens when using ADSI Edit.
Thanks to a tip by Alex Verboon, using Microsoft’s (Sysinternal’s) Active Directory Explorer will allow you to see the settings of this attribute. Download AD Explorer, run the app, on a single domain server you can live all fields blank and click OK.
Click on your domain, then in the right hand window right click on wellKnownObjects”, and choose properties.
In the resulting window you can review the current settings for the default OU’s for Computers and Users
LAN-Tech Network Management 
Comments on: "Locate default Computer or User OU" (1)
Thank you! Nearly three years later and this is exactly what I was looking for!