Windows 8

[◄Chuck►]

Some other thing is, though you don't need a Microsoft account to use Windows 8 in general,
you need it to install apps via the Microsoft Store. That's the default way to install apps
of those kind. There exists a workaround to install them anyway, by setting some policy-value,
which is set by default on Enterprise versions so that admins may distribute software within the company.

However, I see two problems there:
1. Privacy issues, as a particular User-Id is now linkable to a unique Windows installation.
2. Software manufacturers cannot provide their software on a CD or DVD any more without enclosing a manual how to open W8 for 3rd party installations.

While having some sort of store to distribute applications is generally a good idea, I think Microsoft didn't do their homework thoroughly on this one.
Ubuntu basically shows how it could work.