[richiem]

NOTE: This guide is UPDATED -- I had a couple of reasons to have Windows(XP SP3) on an SATA AHCI drive:
1) So that the system would be all SATA AHCI for all drives.
2) So that the two purple JMicron SATA ports on my GB EP45-UD3R board can be used for eSATA connections.
3) So that all my hard drives have the same connections, regardless of OS, making swapping and cloning much simpler.

This works on the Gigabyte EP45-UD3R board with Intel ICH10R controller. It may work for other boards with the ICH10 or the ICH9/ICH9R, too.

Background -- My WinXP SP3 install on an SATA-IDE drive predated my "Frakkintosh" conversion for OSX (now using Chameleon 2 RC4 with Asere's bootloader v1.1.9 to boot Snow Leopard 10.6.4).

I Googled changing WinXP from IDE to AHCI and found various methods and lots of discussion. After trying them all -- regedits, F6 driver installs with the WinXP Install CD, non-destructive system repairs, etc, I gave up -- NONE of them worked for me -- it was either repeated hangs at Verifying DMI Pool Data, or "error reading disk" or "system error" or just one scary BSOD after another. I was probably doing something wrong, but it didn't work.

I read a post on Tom's Hardware about using a second drive controller system for making a controller system change, e.g. from SCSI RAID to SATA RAID, etc. Trouble is, I didn't have a second controller board/system to use. Then it hit me. While this might be obvious to many, I just wasn't seeing it -- my EP45-UD3R has *two* drive controllers already built-in -- the Intel ICH10R (AHCI/RAID controller for the six yellow SATA ports) and the JMicron (IDE/AHCI controller for the two purple SATA ports). To do this conversion for a Gigabyte MB, Windows may or may not have to be on an SATA drive -- I haven't tried using the board's ATA-IDE connector as a boot source for an ATA-IDE drive to do this conversion -- it's worth a try.

Procedure --
1) For safety, disconnect the Mac OSX drive and pull the USB bootloader if you use one.
2) Start up holding down Delete and boot into BIOS>Integrated Peripherals.
3) Enable the "Onboard SATA Controller", which is for the JMicron ports, then set it to IDE for booting the WinXP IDE SATA drive. Be sure to set the Intel ICHxx controller (the top listing in the "Integrated Peripherals") for AHCI.
4) Connect the WinXP SATA IDE drive to one of the purple ports.
5) Boot into WinXP on the IDE drive/controller.
6) Download the newest Intel Matrix Storage Manager for your ICHxx controller; these are the drivers for AHCI and RAID config, and install the package on your Windows system.
7) Reboot into Windows. I had to reboot twice before everything settled down.
8) Connect an SATA drive to one of the yellow SATA/AHCI ports.
9) Use Acronis True Image (or other cloning app that supports lots of drive controllers) running on the WinXP IDE drive to clone it to the AHCI drive.
10) Shut down and disconnect the IDE drive.
11) Reboot with Del and set the "Onboard SATA Controller" to AHCI.

Now you can dual boot OSX and WinXP all under AHCI. Even better, with Sno Leo, OSX can read and write to the WinXP AHCI drive. On the Windows side, HFSExplorer can open the OSX drive for reading and writing.

[DocCoop]

Great - thank you for the neat tutorial!!!