There are tools out there (NTFSDOS comes to mind) that will let you modify an ntfs partition from dos, but they may be read-only... not sure. At any rate, you'll need to find the registry files which (as adholioshake mentioned) are different for different versions of windows. If you can boot to dos, have access to the ntfs volumes (using a 3rd party tool most likely), and know which files to modify you should be golden. Look for user.dat, system.dat, and backups are usually named things like user.1st and system.1st. Make sure to use dir -a when you're looking for them, because they have "hidden" and "system" attributes.
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