Thanks jimp56.
That solved my problem. Now the logon box pops up. A couple of minor corrections were necessary in my case, the "WindowsNT" part of the key had a space in it, so it was actually "Windows NT":
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
And the value was not "ForceAutoLogon", but "AutoAdminLogon"
I add the above, not to be pedantic, but because others that follow may be as lazy as me and try pasting them into the search function.
I also changed the "DefaultUserName", and "AltDefaultUserName" (though I'm not sure what this last does), to my logon name.
Thanks again, I'm happy now, for the moment, though I'm sure I will be plaguing this forum in the weeks to come.
P.S. I found a free utility "ERUNT", that claims to do registry backup and restore for Win2k/XP, much the same as the old DOS "scanreg/restore" did in Win98. The registry can be restored via the Windows Recovery Console, or another Windows OS if it can access the drive. Sounds like a must have to me: