DOS Program Full Screen

I have a client where I replaced two computers with new Windows 7 Pro computers and I installed Windows 7 Pro on two other computers. The client has several DOS programs that they use. I had advised them that they need to replace the DOS programs with newer ones, but they opted to stay with the trusty old programs. I got them running on Windows 7 just fine and they can print without problems. The issue is that when they run the programs they appear in a window that is about 3" by 5". It is too small to be useful. When we hit Alt - Enter, we get the response, "This system does not support fullscreen mode." I have tried running it in XP Mode, and it doesn't help. I still get a very small window. I have also tried running on Windows XP Pro inside Sun Virtualbox. It is the same problem. Has anyone discovered a way to make DOS programs full screen? Is there perhaps a registry tweek that might do it?

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