I did it guys!
It worked perfectly on P5K-VM with ICH9 southbridge. Switched AHCI in BIOS. Then had to reboot AGAIN in BIOS for HDD drive to be detected under a new AHCI section that appeared in BIOS, THEN rebooted to windows finally and finished installing the driver.

First, there is a small issue with the instructions.
Because if you replace the lines in iaahci.inf from latest intel package, you will have two entries with:
"PCI\VEN_8086&DEV_2923&CC_0106.DeviceDesc" at the bottom of the INF.
You must erase the first one and keep the one that you modded and that finishes by this : = "Intel® ICH9 SATA AHCI Controller"
I think it's purely cosmetic for the name of the entry in device manager but it was worth saying.
About the new performance when comparing emulated IDE to AHCI+NCQ, I must say i am mixed.
From MY feeling, it is much faster especially when cold booting windows, maybe 10 seconds less.
But then i checked the drives performance under HDTune, and strange results, the Burst Rate is bad with AHCI!!!
What's going on??
My 2 HDDs are Samsung sata drives with NCQ support.
Apart from that, my IDE DVD-RW Drive still works the same, no problem.
I am going to try making a backup with Ghost 2003 now...
See you,
TSR
This post has been edited by theshadowrunner: 04 April 2008 - 11:44 AM