While this is no longer possible with Windows Activation Technologies in Win 7, Windows XP allows using Hardware Profiles for a shared installation that can be run either physically or virtually (e.g. using the KVM virtualization stack built into recent Linux kernels, which is a lot more convenient than VMWare Player with its kernel module dependencies, at the price of 3D graphics acceleration).
The recommended sequence for such a setup:
virsh editto change the original disk configuration from
<target dev='hda' bus='ide'/>to
<target dev='vda' bus='virtio'/>(and drop the dummy device).
Switching the physical Windows setup from IDE to AHCI cannot be achieved in that easy way, if you have an AMD SB800 south bridge that has different PCI device IDs for IDE (4390) and AHCI (4391) mode (consequently thwarting parallel installation). There, some registry tweaking is required after you have copied
ahcix86.sys from the unpacked AMD driver package to
"DisplayName"="ATI AHCI Compatible RAID Controller"
With the AHCI driver thus enabled, you may reboot and switch the BIOS SATA setting from IDE to AHCI without facing the typical "Unknown boot device" BSOD in result.