What I would do is create an unattend file that has everything but computer name or product key filled out. For the WinPE side, you can use the default installation key, but do not put one in the OOBE section. This is only if you are not booting to audit mode. Then what happens is that after the install is done, when Windows Welcome comes up, it will ask you for Computer Name and Product Key only and then go to the desktop.