Well, I'm not sure how it works with MPS systems in there.
What I would do is disable ACPI in the BIOS after flashing then once in Windows go to Device Manager and change the MPS Multiprocessor System to Standard PC and reboot. Once back into Windows switch BACK to MPS Multiprocessor System and reboot again.
I'm not sure if that will work but it should. Only reason it wouldn't, in my thoughts, is that MPS needs ACPI if it is available which I see no reason it would.
This might work and might not. If Sandra is installed you could check the system information module to see if it says ACPI aware BIOS. If it doesn't...you're in business. One of those first three modules (system info, mainboard and another I can't remember the name of as I'm at work and don't have it here) give you that information.