Answers:Windows XP SP3 is fully compatible with the SATA AHCI Mode, but contrary to Vista it doesn't natively have the needed SATA AHCI drivers. So you have to load them during the XP installation (via floppy/F6 method) or - as the better option - to integrate them into the XP-CD. I assume, that you got the BIOS message, because the vendor of your system has preinstalled Vista and is not interested in any support traffic from users, who are not able to get XP installed in AHCI mode (due to missing or wrong AHCI drivers). Regards Fernando Fernando, thanks for your quick response, I will then integrate the AHCI SATA drivers to my Windows XP SP3 to see how it works ... Greetings