[eliprand]

my own experience as of 4/20/08:
Mobo: Gigabyte GA-EX38-DS4
BIOS: whatever came with it, no upgrade
Intel Matrix Storage: 7.8
OS: Vista Ultimate 64-bits edition

I first installed Vista 64-bits edition on my primary drive (10K WD-150GB).
I did not plug my 2x160GB HDDs at this time.
Fully installed the OS, not hick-ups.

I followed the instructions on this forum to first enable AHCI, just to see how it went.
I did enable the AHCI setting in BIOS after I installed the drivers (including the registry key thing).
Rebooted.
OK.

Connected the 2x160GB HDDs (after power-off, no hot-plugging here...) and they were recognized by the system.
I tried to simply flip the BIOS setting to RAID but Vista wouldn't boot.

At this point, I did install the full fledged Intel Matrix storage v7.8, just in case...
The install did work and everything was good, but still no RAID.

So I went around and while looking at the previous post, I came across the iaStorV entry, labeled "Intel RAID Controller Vista".
I thought it was a good bet!
So I went on and set "iaStor" Start to 0x4 and switched "iaStorV" to Start=0x0
Rebooted, switched the BIOS to RAID and all worked.
I let Vista go through all its updates and all and went on to configur my array(s).

Hope those steps will be helpful to others. I must admit that I was kinda nervous when I performed the final step to enable iaStorV instead of iaStor... so, don't be!