DOSBox is a DOS-emulator that uses the SDL-library which makes it very easy to port to different platforms. DOSBox has already been ported to many different platforms, such as Windows, BeOS, Linux, MacOS X, etc.
DOSBox also emulates CPU:286/386 real mode/protected mode, Directory FileSystem/XMS/EMS, Tandy/Hercules/CGA/EGA/VGA/VESA graphics, a SoundBlaster/Gravis Ultra Sound card for excellent sound compatibility with older games. But DOSBox isn't restricted to only games. You should be able to run any DOS application in DOSBox - in theory at least as the emphasis has been on allowing you to run your favorite DOS games smoothly. This fact means that communication, networking, and printer support are still being developed.
You can re-live and maybe even enjoy the good old days with the help of DOSBox; it can run plenty of the old classics that are unable to run on your new computer.