Install TFS Powertools on your TFS Server!!!
Powertools has a add-in that automates this whole process, and can be managed and scheduled from within the TFS management tool.
EDIT: When you install TFS powertools on your server, the docs are not very clear. After you do this, open up TFS admin tool, and you will notice a Backups section that was not there before. From there, you can define your backup model, tell it what to back up (it will walk you thru a wizard), and it will schedule the backup for you. It basically automates all the steps in the MSDN doc you reference.
As a side note, install powertools as a base install on every machine that uses TFS as well. It has the shell extentions, and a ton of functionality that is very useful for TFS users, not just administrators.
It might even make you love TFS, if that's possible. We are successfully using it for full SDLC - work items, source code, workflow management, build management, etc.