Install Vista Ultimate w/o SP1 on Machines with AHCI Enabled

The Advanced Host Controller Interface (AHCI) is a programming-specification which defines the operation of Serial ATA host-controllers (also known as host bus adapters) in a non implementation-specific manner. The specification describes a system memory structure for computer hardware vendors to exchange data between host system memory and attached storage-devices. (excerpt from wikipedia)

Vista Ultimate w/o SP1 cannot be installed directly on a machine with AHCI enabled. You'll probably get a bluescreen crash during boot. However, you can do a trick to work around this problem. Here are the steps:

1. Disable AHCI in BIOS. You may have to disable Flash Cache Module as well.
2. Install Vista Ultimate (w/o SP1).
3. Start the registry editor, and set the value of "Start" to 0 in HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci.
4. Install AHCI driver. After that, you should be able to see msahci.sys under C:\windows\system32\drivers.
5. Restart your computer, and enable AHCI in BIOS.