Regress from "RAID-Ready" or AHCI to IDE

Is there some way to regress, revert, or go back from a "RAID-Ready" or even
AHCI setup to a plain old IDE setup in Vista Ultimate (x64) w/ SP1?
Searching the internet, I find tons of material for going from IDE to AHCI.
Most of that revolves around the steps from:

http://support.microsoft.com/kb/922976

Specifically,

"To resolve this issue, enable the AHCI driver in the registry before you
change the SATA mode of the boot drive. To do this, follow these steps:

1. Exit all Windows-based programs.
2. Click Start, type regedit in the Start Search box, and then press ENTER.
3. If you receive the User Account Control dialog box, click Continue.
4. Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
5. In the right pane, right-click Start in the Name column, and then click
Modify.
6. In the Value data box, type 0, and then click OK.
7. On the File menu, click Exit to close Registry Editor."

But, there's almost nothing about going the other way (from AHCI to IDE).
The little I've found on it basically says to do the very same thing as
above with some variation in the entry in the Value box (I've seen
references to 0, 1, and 4). But, none of them let me change the Drive
Configuration of my single SATA drive in the BIOS back to IDE (Native) mode.
All that ever happens is a blue screen and reboot until I set the BIOS back
to RAID. I've also seen people claim they can go back and forth from AHCI
to IDE mode simply by changing the BIOS (no registry changes). But, my
guess is that they somehow got all necessary drivers loaded into the system
initially, and haven't installed Intel's Matrix Storage Manager.

I've got an Intel DP45SG motherboard and I did the initial Vista install
with the BIOS set to RAID (so no IDE drivers have ever been loaded into the
OS). My single SATA drive has never been added to any kind of RAID array (I
selected the RAID option because I wanted my eSATA connection to support
hot-swapping and Intel's documentation said I might as well use RAID instead
of AHCI in case I ever wanted to set up an actual RAID array). As an added
complication to what drivers are in use, I also installed Intel's Matrix
Storage Manager.

[Glip]

I had the same problem on my motherboard with AMD 785G chipset. I set it to AHCI during Windows install, but the drivers for this chipset have a problem coming out of stand-by with AHCI configurations, so I wanted to revert back to IDE.

First I set two of the SATA ports to native IDE, so it would at least install the drivers for IDE. This went fine. Then I changed the driver for the AHCI standard storage controller to the "standard dual channel IDE controller" driver. Then I switched over the previously AHCI configured drive to an IDE port, but the system wouldn't boot. After having tried several things with Windows system restore and trying the last known good configuration setting, it wouldn't boot, complaning about a missing bootmgr. Then I simply tried to set all SATA ports to native IDE and it al worked. So I don't think any drivers are necessary; what I did wasn't needed. I guess going to IDE is more simple than vice versa.