What about multi-users on a single PC?
What happens if your home computer is shared so that each kid has their own account? And you have a laptop as well? Do you have to install one version per user on the desktop AND a version on the laptop or does one on the desktop cover all users of that machine, and it will handle them having their own Live account?
They best think this through before making it so difficult and confusing that LibreOffice, OpenOffice and Google Docs are vaible alternatives.
I think I better go out and buy Office 2010 while I still can!