That's not a very smart thing to do.
- Did the upgragde to Windows 8 delete the original files on the hard disk Windows is installed on?
- On what disk is that .bkf file?
- What files are in that backup file? You realise, of coiurse, that you can't restore any file from the Windows or the Program Files folder?

Anyway, http://www.techrepublic.com/blog/windows-and-office/restore-a-windows-xp-backup-in-windows-8/ tells about a free way to do it. So there is no need to buy any third party program that might be suggested by members selling it.

Since the backup offered in Windows 8 is very different from the backup in Windows XP, I advice you to reconsider your backup methods.

Kees