Windows 7: Dual boot with WIn 7 & XP

I have win 7 installed in my PC on C: drive. I have a empty D:drive with 102 GB of space, in where I wish to install Windows XP. But during the installation process I came across with a error " setup could not find any hard disk". Upon research I find that SATA controllers in new computers doesn't support XP installation. In one of the forums they suggested to change SATA module in BIOS to modify from AHCI to ATA. When I try to do that it popped a statement " cache flash module" has to be disabled. I disabled it and modified the AHCI to ATA , which resulted in another pop up saying that " these setting changes will result in reinstallion of existing operating system" . Please advise on a procedure where i can install XP into D:drive without loosing the existing operating system. Thanks.

You will need to set your BIOS back to what it was configured to before (otherwise Windows 7 may not boot), and you will need to provide drivers (via F6) during the initial phase of Windows 7 setup from a floppy disk. Otherwise, you will need to slipstream them into your XP installation disc (nLite is good for this) and then install with the new setup media created with the XP-specific SATA drivers for your system. Given you have not filled out your system specs, I cannot give you any further details.

Have you tried virtualizing any XP programs which will not run in Windows 7 Compatibility Mode?

XP mode comes with Ultimate or Pro versions, otherwise VMWare, Virtual Box and Virtual Player are good freeware to try.

First check for all the Win XP drivers for your hardware on the manufacturer's web site.
If your Win XP CD, does not support your Sata Controller, you will need to load drivers to uses at F6.
Load Sata Controller drivers with a floppy disk is the best way.
SATA Drivers - Load in Windows XP Setup on Dual Boot

OR
SATA Drivers - Slipstream into Windows XP CD