Windows XP does provide support for a few of the controllers from Qemu, perhaps one of the others could work.
You likely do not need to recreate the system entirely but find which controller can boot successfully. IE use an acronis/gparted iso or ddrescue to mount two drives on separate controllers and clone the original image to one hosted on LSI, PIIX4, or Virtio controller. Acronis etc can adjust boot sectors to fix boot issues in case that is part of the problem and should also have drivers for these controllers. Perhaps uninstalling the drive controller from a cloned image on virtual box's end and shutting down before booting in qemu could help.
