I have a Think Pad T420 with dual boot option of Windows 7 Pro and Windows XP Pro both 32-bit. However for me to boot into Windows 7 I have to set the SATA configuration in the BIOS to AHCI Mode, but that will cause the XP to BSOD with the error of unable to detect hard drive. I change the SATA configuration to Compatibility and Windows XP can boot successfully but Windows 7 BSOD with the same error. I cannot seem to find the right driver for the AHCI chipset for Windows XP. If anyone could offer any assitance, that would be great.