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