For most of people who forgot to install AHCI / RAID drivers during Vista installation using F6, it is possible to enable AHCI for previously installed Vista running IDE mode. This is outlined by Microsoft Knowledge Base #922976 ( http://support.microsoft.com/kb/922976 ). I have enable AHCI mode for Dell computers running Vista already following above instruction. So naturally, I tried to enable AHCI for mac pro running Vista. After enabling Microsoft AHCI driver as instructed in MSKB #922976, I extracted AHCI driver from Intel matrix storage manager and manually updated ESB Ultra ATA storage controller driver with iastor driver. This seems to enable AHCI for Mac Pro running Vista under device manager. However this disenabled IDE for CD drivers. Sure enough Microsoft has KB #928253 for "SATA optical drives are not available after you start a Windows Vista-based computer". Unfortunately even with this hotfix, my Mac Pro couldnt access or find CD drivers. So my question is has anyone successfully enabled AHCI for Mac Pro running Vista?