When attempting to reboot one of my computers, I get the following:
Windows could not start because the following file is missing or corrupt: \windows\system32\config\system.

You can attempt to repair this by starting the window's setup using the orginal setup CD-rom.

Select "r' at the first screen to start repair.

I did this and it says it cannot repair it.

Hello,
Is the disc that you are trying to use an original XP disc, or a recovery disc?
The disc that you are using may not have the recovery console.
Here is a web site that you can download and burn an ISO of the recovery console.
Choose create an xp repair disc from the many options.
You will want to run sfc/scan now from the recovery console.