Today I decided to finally give AHCI a try on my Vista setup. Unfortunately I've installed Vista with no AHCI support enabled in the BIOS, so no drivers were installed by Vista for this very mode automagically.
How difficult can it be? Reboot, Enable AHCI in the BIOS, Boot back up again: Boom - Bluescreen. Here is something I can't get, why does Windows bug me with plenty of useless dialogs to confirm or cancel but does reboot automatically about 2 seconds after throwing a Bluescreen which IS actually important? If you are lucky, you can catch a glimpse at the error message for about 1-2 seconds but if your shiny new TFT is busy synching to the new video mode you won't even notice it!
This can be fixed by adjusting the Crash Control Registry settings:
Set AutoReboot to 0.
OK, next time I will be able to read which component did cause the Bluescreen. Nevertheless I started looking around for others having problems switching to AHCI. Aside very adventurous solutions like moving the boot device to a separate SATA controller, enabling the AHCI mode on the other and booting up so Vista can install proper drivers or hacking the hell out of the Registry and some Intel-Raid application I have found a way more convenient way to enable AHCI.
It turns out that Vista will disable AHCI support for good if you did not had it enabled during the setup. To switch it back on you will need to do one tiny Registry Hack:
Set Start to 0
Yes, 0 to enable it. Don't ask.
Reboot, toggle the AHCI Support in your Bios and everything should be fine.
I don't know if this is related to this issue, but I have installed the Intel Chipset Drivers some days ago. It might be necessary.