Deleted files aren't actually deleted in most cases, which is why a multi-terabyte file can be "deleted" in a second with the hit of the button. Windows just stops pointing to it. The data is still written on the physical disk in most cases. The update just needs to get Windows to point at the missing files again.<br><br>PSA: If you're getting rid of a hard disk and are paranoid about your personal data, it's best to do a low level format, or zero format, write a huge dummy file over the whole disk, then put a drill through the platters.