[Rubber Duck]

There is an impelling logic to releasing the OEM version early. None of these machines start with any data or any mission critical functions. Not only that but the machines are going to be primarily aimed at the domestic market. Between release and use in earnest most machines will sit around idle for a couple of months which give Microsoft ample time to come up with a few critical updates.

If you buy Vista out of the box, however, it could be used to overwrite an operating system that is running mission critical functions and manages large amounts of important data. That is a different cup of tea altogether.