If you need to run an MS-DOS program on x64, check this out. As the article points out, this is different than vDOS or DOSBox--it is not an emulator. The guy who wrote the article is a professor in the English Department at Columbia, so he's mainly "just passing on the information".
Run MS-DOS programs on 64-bit Windows with NTVDMx64
Run MS-DOS programs on 64-bit Windows with NTVDMx64
