Need to repair Windows XP but don't have original setup cd

So I misplaced my original setup cd and now my PC won't start and returns the error:

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

Is there any way to resolve this without buying a fullprice Windows CD? Thanks again for your input