If I browse to the Open XML SDK 2.0 for Microsoft Office page and select "Other Versions" > "Office 2007", it takes me to Open XML Format SDK 1.0. Does this mean that the Open XML SDK 2.0 for Microsoft Office does not support Office 2007 officially?
Edit:
It would seem that it is valid to work with Office 2007 but that still makes me wonder about why the above happens, just to suggest you should use Office 2010?