Major file corruption

I got an HP Pavilion xt926 from a friend because there is something wrong with it and he didn't want it anymore. So when i started it up it said,

Windows could not start because the following file is missing
or corrupt:

\WINDOWS\SYSTEM32\CONFIG\SYSTEM

You can attempt to repair this file by starting Windows Setup using the original Setup CD-ROM. Select 'r' at the first screen to start repair.

The problem is i don't have the Windows Setup CD-ROM and my friend doesn't know where it is.

Is there any alternative way of repairing this file or is there not without the CD-ROM??

I'd appreciate any feedback

Greg