In Windows 8, you can configure what account you use to sign in to the Operating System.
You can get to this from the Charms > Settings > More PC Settings > Users
You can switch between a Windows Live account (or Windows Account or Hotmail) and a local account (non web account).
You can change the user sign-in options.
Three things you can change here:
You can also add multiple user accounts to your device. This will allow you to have multiple users able to sign in to your PC, Laptop or Tablet.
This is where I think Windows 8 will have a strategic advantage compared to the iPad.
As you all know, the Apple iPad only allows for one owner/user.