Difficult.
Probably what you'll end up doing is fitting the old disk to the new computer and rescuing as much of the profile as possible, piecewise - IOW, boot into XP and copy the old favourites, documents, desktop icons and whatnot across from the %SYSTEMROOT%\\Profiles\\%USERNAME% directory.
I can't see a direct migration being possible - unless the XP Files & Settings wizard can work with an existing directory on the local box.