Created an attachment (id=8071)
I've replaced Windows (Server 2003 SP1)'s driver with the official debug build of UniATA 0.43a1.
Running the "usual" PIIX3 configuration in VirtualBox, this gives (after a loong attempt at booting. 10 minutes or so) the INACCESSIBLE_BOOT_DEVICE bugcheck.
Attached is the full debug log. Not sure what else to do about this, or if I'm perhaps doing something wrong.