Are you using Windows Vista and you are not able to run DOS based programs in your Microsoft Vista PC? I would suggest DOSBox is the solution for running DOS based programs.
What is DOSBox?
It is a DOS emulator and it works well with almost all platforms. The application already ported to Windows, Linux, MacOS X etc. Ultimately it works with Windows vista too. This application overcomes the ambit of running DOS based application in Windows vista, however the application does have some compatibility issues with Windows Vista. So I can’t guarantee that all DOS based programs works.
I hope somebody experiences problem for DOS based games in Windows vista. Just download and install the DOSBox and run the DOS based programs after that.
Another ultimate solution to resolve this is installing a Virtual PC in windows vista itself. After installing Virtual PC you can install any operating system in Windows Vista. Create a virtual partition and mount DOS operating system. DOS operating system is free for download from Microsoft.