How to recover from a corrupte

How to recover from a corrupted registry that prevents Windows XP from starting

While I was shutting down my computer, the power failure happened. When the power back on, I tried to boot my computer. It failed with this error message:
Windows XP could not start because the following file is missing or corrupt: C:\WINDOWS\SYSTEM32\CONFIG\SYSTEM

To solve this problem,
1) I booted the Windows XP Professional installation CD from CD-ROM trying to repair the system registry, but I was told that the hard disk is not accessible or does not exist.
2) Then I booted the NT Password & Registry Editor (LINUX) from CD-ROM to access the hard disk, but the list of hard disks shows nothing.
3) I booted the Chinese Windows XP Professional setup CD of Shanghai Government version form CD-ROM. It’s included ant-virus software can scan files from my hard disk.

By the way, this is a DELL Dimension 4200 PC.

I have read the following pages, but they did not help me:
http://support.microsoft.com/kb/307545/
http://support.microsoft.com/kb/322756/
http://support.microsoft.com/default.aspx?scid=kb;en-us;307545

Since I do not want to lose any data, how can I repair or reset the registry to get hard disk to boot? Or it is another problem?

Thanks