Dell 9150 won't boot from HD or CD

A few days ago my 9150 with XP Pro SP3 failed on startup with the unsuccessful start up message asking if I wanted to start normally or in safe mode, etc.  None of that matters because it next says \windows\system32\config\system file is missing or corrupted.  No new software or hardware have been added recently.

I have tried everything from booting from CD which loads all the necessary files but does not show the HD in the list when I try to install.  therefore I can't even get to windows.  I have run full diagnostics and booting from the CD using F12,  Typing R takes me to a C drive prompt and doesn't get me to the Recovery console.

I know the drive is o.k since I have run diagnostices 3 times and I also installed it in another PC where it behaved the same way as the boot drive.  I was able to use it as a slave drive and copied some of the files I wanted to save, but couldn't find the right "My Documents" File which had a number of important files in it.  I'm stumped.  I'm pretty sure it's a software corruption problem but I want to recover the material in the My Documents file so I don't want to dump the drive and start all over.  Anybody have any ideas?  I'm stuck. 

I hope someone has an idea