Changing the onboard SATA in the BIOS to ATA mode rather than AHCI is only a workaround to the real issue.  There is potentially greater performance (although arguable today) with AHCI, so just switching to ATA mode is not the real answer.  Also, not all BIOS' have that option, so it is good to know how to make it work. You do not necessarily need a floppy to provide that driver, but that is the only way that Windows XP can find and load one at the F6 prompt, which is Windows built-in way of loading support for those types of devices.  You can use nLiteOS.com to integrate drivers into your install media - ideal for loading storage drivers (and/or required Service Packs) when installing XP/2003 on systems with no floppies. The driver you need is on the following Driver and Downloads page, under SATA Drives, Matrix Storage Manager: [URL]  
Hello,   My Dell came with Windows XP.  I upgraded to Windows 7 about 6 months ago, but now would like to revert back to XP; full clean install.  However, when I try to install XP, I get a message that no hard drives could be detected.   Is there a way I need to configure my BIOS, software I need to run, etc.?   Thanks in advance.
Using Win 7, but would like to install to XP; cannot find hard drives issue