You have to make sure you get the right version msconfig.exe
It should be located here:
C:\WINDOWS\PCHEALTH\HELPCTR\Binaries
But could also be located here:
C:\WINDOWS\system32\dllcache
and if you upgraded to Service Pack 1 for Windows XP, it may still be located here:
C:\WINDOWS\ServicePackFiles\i386
If you still can't find it, you may have to expand the file from the Windows XP cdrom, although I don't know what CAB file msconfig.exe is in.
Or you could run a repair on Windows XP
Normally, the easy way to restore a file is too use MSCONFIG and use the EXPAND FILE button to do the job. But with that file missing, you might have to do this the hard way
Notes on Expanding files:
Expand
Extracts a file from a compressed file. Use this command to extract a driver file from a cabinet (.cab) or compressed file.
The expand command with the parameters listed below is only available when you are using the Recovery Console. The expand command with different parameters is available from the command prompt.
expand source [/F:filespec}] [destination] [/d] [/y]
Parameters
source
Specifies the file to expand. Use this if the source file contains a single file. Source can consist of a drive letter and a colon, a directory name, a file name, or a combination. You cannot use wildcard characters.
/f:filespec
If the source contains more than one file, this specifies the name of the file you want to extract. You can use wildcards for the files you want to extract.
destination
Specifies both the destination directory and file name for the extracted file, or each individually.
/d
Lists the files contained in the cabinet file without expanding it or extracting from it.
/y
Suppresses the overwrite prompt when expanding or extracting files.
Examples
The following example extracts the file Msgame.sys from the Drivers cabinet file on a Setup CD and copies it to C:\Windows\System\Drivers:
expand d:\i386\driver.cab /f:msgame.sys c:\Windows\system\drivers
The following example expands the compressed file Access.cp_:
expand d:\i386\acces.cp_ c:\Windows\system32\access.cpl
The following example lists all the files in the Drivers cabinet file on the Setup CD:
expand /d d:\i386\driver.cab
Important
The Driver cabinet file, which contains most of the drivers provided by Windows, includes thousands of files. Expanding all of the files from this cabinet file onto your hard disk will take time and a lot of disk space. It is recommended that you extract only the file you need from this file.
Notes
If the destination is not specified, the file is copied to the current directory.
You cannot specify removable media such as a floppy disk drive or a CD-ROM as the destination.