Dell XP-Home Unique recovery problem

I have encountered a somewhat unusual problem with my daughters computer (Dell 3000 XP Home).

We had run SUPERAntiSpyware on the system and found that the computer had many incidences of trojan infection .... many of which were in the register. We allowed the tool to quarantine the infected files. Then when we did the restart and tried to reboot the machine, we got the message saying that the SYSTEM file was missing or corrupt. So we hunted/found the original system XP CD and did the recovery\repair thing. We set up a tmp directory where we saved the corrupt file(s). These were the config SYSTEM, Security, Sam, Default, and Software files. We then copied/replaced those corresponding files from the XP repair files into the config area.

With that done, we then rebooted the machine. The system came up fine and everything seemed to be in tact. Both the system files and the user files were there and accessible. The only problems seemed to be that the regular user sign-on screen was not present, and also, the desktop.... although it had all the system file Icons ..... it did NOT have any of the previous User Icons. So ....although this was not a REALLY big deal, we decided that since our original error message, after having quarantined the infected trojan files, had specified ONLY the Windows\System32\Config\SYSTEM file as being corrupt ..... maybe we should copy the OTHER Config files (Software, Sam, Security,Default) BACK from the Tmp directory where we had stored them. We did this .... and this is where we ran into trouble. After doing this, we tried to reboot, but now get an error message saying essentially that there is not a "match" on the password (even though it previously never even REQUIRED a password). And, as far as we know, there never was a password set on the system. So now we are not able to gain access to the files EITHER through the XP recovery/repair mode OR the normal boot process<frown>. It now asks for an administrative password and whereas before it was OK with just hitting the ENTER button ... it nows gives a password error.

I THINK all we really need at this point is a way to be able to access the recovery mode (as we had previously been able to do) in order to again to re-copy all the five files from the REPAIR area. We would be especially grateful if you could give us any tips on how to get back into the system and re-copy these files.

Lastly, I am embarrassed to say that this computer has about four years of my daughter's user data and pictures on it ..... that have never been backed up <frown>. So, I am sure you can appreciate how much your help would mean to us.

Thanks in advance .... for any attention you may give our plea/request.
/JPMM