Last thing done to the system was to migrate the system disk to the temporary HDD so I can do the following:

* convert the dual-boot setup to a single OS setup (getting rid of Windows 7 and editing the BootManager entries on the Windows 10 partition)
* convert the Windows 10 partition (now single boot) from BIOS/MBR to GPT/EFI
* Migrate the EFI/GPT setup to the NVME on the new proposed build (this one may be a tad iffy, but we'll see)

She has the gaming system, but with the original mainboard and the temporary HDD, mainly because we ran out of time for the final part of the migration for the day.