Transferring virtual disk from one mac to another

I have been trying to transfer a virtual instalation of XP from one hard disk to another. Unfortunately the only one of my macs capabale of using parallels hung in the middle of a leopard upgrade and it seems I will need to delete my disk. I am therefore eagerly trying to rescue some key files from the disk before I do so. When I try and move the file with the thame winxp.hdd which I understand is the only file I need, it is listed on the original disk as 18GB or so but on the new disk each time I try it is only 8GB or so. Has something happened to the file? Wil it work? Or have I lost my instalation? Anything I can do to rescue the file (have tried using a target disk mode as well as using a usb drive and disk utility to create images.

 

Try and see if it will work.