BY FAR the most common problem on Windows machines is a bad sector developing in one of the registry files. If you don't have a usable backup of same then you're hosed no matter what else you do.
So I would suggest a slight variation on the procedure:
1. mount the drive from Ubuntu (see details above)
2. try to copy all the registry files from "\windows\system\config" to someplace/anyplace else. If one of them fails to copy then you know which file needs to be replaced; if none of them fail then maybe the ntfsfix is all you need.
3. *IF* the Windows machine had System Restore enabled then you'll be able to find a backup of the registry files in one of the "\windows\System Volume Information" sub-folders. Otherwise, you can also try the folder, "\windows\system32\repair", which always has a backup (though by default it's only the initial most-basic version; I run NTBACKUP on every Windows machine I touch so as to update this 'repair' backup)
4. try to rename the damaged file, i.e., leave it in-place but unused.
5. copy the backup of the damaged file to the "\windows\system32\config" folder
6. run 'ntfsfix' (to trigger the built-in Windows Check Disk on next boot)
7. reboot the machine
8. cross fingers