My understanding is that Microsoft "Office" is an "Office" of software (i.e., Word, PowerPoint, Outlook, et al). However, I am not aware of Visio being a part of that "Office" suite of software. I have always known it to be a standalone software (i.e., Professional and Standard versions only) of the Microsoft family.
Note: After the original posting I visited
http://office.microsoft.com/en-us/pr...101825692.aspx where it notes that Visio is not part of the Office family but, as a "related" product. So, I think you can scratch "Microsoft Office Visio" off of your list.