Hi Pete and welcome!
I am not sure what you mean by DOS generated, but I am assuming you mean the program is running under DOS, or a DOS window, and prints via a parallel printer interface.
It is also not possible for us to be specific when we don't have the specifics of the computer you want to run this program on. Ultimately, you should probably upgrade your program so that it runs under Windows. Attempting to support legacy software will do nothing but get harder, and more expensive, as time moves on.
That said, entering
DOS printing in XP into Google might give you some ideas - or create more questions! But that's good too.
Also, check out,
DOS print USB Windows printers.