Move mailboxes to another container

There isn't anything built into Exchange that allows this.

You can move the mailboxes using the exmerge utility (found in the Microsoft BackOffice Resource Kit). If you want more info on exmerge, just go to the Microsoft KnowledgeBase online andsearch for exmerge.

Another possibility is to purchase a third-party package, such as Bindview.

I'd also suggest that you put all of your mailboxes back into the default container, and keep them there. Organizing mailboxes via containers is problematic, as you're finding out. If you want to organize your users view of the Exchange organization, address book views are a much better bet.