I recently had to set up an original honest-to-god IBM AT computer so I could extract a copy of the ancient computer game "jet" from an old HDD for a friend that was setting up an old computer as a display for a museum
The drive had been untouched in a static bag since it was packed before moving here from NewJersey in September of 1995. the files recovered perfectly.
as for "new systems" I've learned enough that before first power up on the OS
on a new computer I actually open the optical drive with a release pin and make my first boot with a clonezilla disc and snatch a clone of the un-initialized operating system installation.
Why do I do that? on Dells and HP's that OS install is "preactivated",
but not yet "married" to the MoBo Serial number.
consider the deeper ramifications and implications of that fact...
But also that it's also preloaded with a rather specific set of chipset
and other hardware drivers... so while you could use it on another computer the hardware needs to be indentical for it to work right.
Manufacturers are LAZY you don't actually think they copy an OS onto each of 125,000 HDD's already installed into the computers one at a time do you?
Nor do they expect new computer owners to have to flip the case over and
type in that 25digit alpha numeric code...