This is an addendum to the question I asked earlier - XP out - NT in. I not only want to remove XP from one of the partitions and install NT in its place, I want to be able to run either system as needed. The reason for this is that I have a program that will not run on XP but will run on NT.

I have a program that will not run on XP but will run on NT.
Have you first tried XP's NT compatibility mode available under the file properties for your application's executable?

You could have added to your original post
https://www.askmehelpdesk.com/windows/off-xp-nt-307677.html

Would you mind using language I can understand. I am not very computer savy.

XP has options for running executable files (programs) in compatibility modes for previous Windows versions. Using Windows Explorer, right-click the executable file of your application (file ending in a .exe extension that is the program), choose 'Properties', select the 'Compatibility' tab, and select the desired compatibility mode. These modes are no guarantee the application will work however, and the other options on the tab may need to be tried in various combination to find out if any will work, but these are worth a shot before formatting/installing NT. If your hardware is recent, finding NT drivers could be a problem. Also, having NT on a production system is somewhat of a security risk as Microsoft no longer supports it.