AHCI is fully supported in Microsoft Windows Vista and the Linux operating system from kernel 2.6.19. Older operating systems like Windows XP require drivers written by the host bus adapter vendor in order to support AHCI. Windows XP requires the installation of a vendor-specific driver even if AHCI is present on the host bus adapter because Windows XP was released before Serial ATA was invented.
By default, MS Vista and 7 have the Msahci driver disabled.
So, how to enable AHCI if you already install Windows Vista/Windows 7 using IDE interface.
Solution…(Always back up the registry key prior to making changes)
1. Exit all Windows-based programs.
2. Click Start, type regedit in the Start Search box, and then press ENTER.
3. If you receive the User Account Control dialog box, click Continue.
4. Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
5. In the right pane, right-click Start in the Name column, and then click Modify.
6. In the Value data box, type 0, and then click OK.
7. On the File menu, click Exit to close Registry Editor
Restart and go into the BIOS and make the changes from IDE to AHCI and restart and away you go.
I've made the change and no problems thus far, but I have not noticed any change in performance.
Hope this helps.