Ok, enough back story. How do you actually perform the link? It depends on the tool you are using.
* If you're using the "old-school" interface that comes in the box with Windows 2000 or Windows 2003, then, once you right-click over the level (ie: Site, domain, or OU) and select Properties, and click the Group Policy tab, you then simply select the "Add" button.
* If you're using the new-school GPMC (Group Policy Management Console) you right-click over the level (ie: Site, domain, or OU) and select "Link an Existing GPO".
Then in both cases, just select the existing GPO, which lives in the "Group Policy Swimming Pool" of the domain.
This was first published in January 2004