This is starting to make more sense.
This machine's BIOS does not have "RAID Autodetect/AHCI"; it only has these two options:
1) "RAID Autodetect / ATA = RAID if signed drives, otherwise ATA"
2) "RAID On = SATA is configured for RAID on every boot"
... so if I set it to #1 above, and it doesn't see "signed" drives, it uses ATA, and my factory installation of Windows does not have ATA disk drivers, thus the BSOD with STOP code 7B?
What is a "signed" drive? Where on the drive is the "signature" ?