I downloaded the x64 trial. I didn't get any patches or updates. Then I restored my own x64 backup with "replace all files" and "to original location".
However, although all my apps have been restored, the old user accounts have not been restored. It logs on only as the admin account I created during the new install. No other user accounts are available. The folders for the user accounts have been restored, though I can't seem to locate the paths you mentioned where the keys are stored. using the Certificates MMC snap in, I can't find the needed certificate, and needless to say it doesn't appear in internet explorer Tools/Options/Content/Certificates
Note also that when I earlier tried 32 bit xp first, after restoring the x64 backup the error I got was that \system32\ntoskrnl.exe was missing, which it was, which made me wonder if all the necessary system files had been backed up.....
This is really a nightmare. But thanks for your advice !!!