Office 2007 products changed the traditional buttons menu for a innovative tabs interface that sorts all old and new tasks on different categories; this change caused that user for most of the Office Family products required training on how to perform common tasks amongs the new features included on this version, something that no previous version of Office required and very similar on what happened with Vista.
While I consider required a training for products like Excel, Access and Word, a training for Outlook 2007 it doesn´t come to my mind as necessary, because most outlook users just read and send emails.
However some outlook veterans and / or first time users will find Professor Teaches Outlook 2007 really usefull and maybe won´t mind paying 20 bucks for the product. Dont get me wrong, the product achieves what it promise through interactive menus, practices and samples with a voice guided lessons, however must of the information provided can also be found in outlook help or on youtube videos for free.
If you are an individual and need to learn outlook 2007, Professor Teaches is really a good alternative, however if you have an small business or big company I would suggest to get the complete office package discounted, you will find really good savings and maybe the Outlook course will be free or for a minimum price.