I think I understand the problem. We are using an original system hive with current other hives. I can get you into the system and your data will be safe, but Windows will be essentially back to the way it was when you first loaded it. You'll have to reformat and reinstall after retrieving your data - is that okay? I'm about to shut down for the evening so let me assume the answer is yes.
Go back to the RC and do the following commands:
COPY C:\WINDOWS\REPAIR\SAM.BAK C:\WINDOWS\SYSTEM32\CONFIG\SAM
COPY C:\WINDOWS\REPAIR\SOFTWARE.BAK C:\WINDOWS\SYSTEM32\CONFIG\SOFTWARE
COPY C:\WINDOWS\REPAIR\DEFAULT.BAK C:\WINDOWS\SYSTEM32\CONFIG\DEFAULT
COPY C:\WINDOWS\REPAIR\SECURITY.BAK C:\WINDOWS\SYSTEM32\CONFIG\SECURITY
That should do it, but any programs you installed will no longer be installed, etc. If you still have problems getting in you - OR if you don't want to reset the OS to it's initial state, try a repair install (boot to the XP CD and choose the second repair option and allow XP to install on top of itself).