When people are into XBox and PS2, few of us who grew up with old dos games with 16 colors and those classy 8 bit music still miss them. Infact I had couple of friends who still play with the old game set of them. Same way there were lot of Dos games which dont work now.
Keeping all these things in mind, DOS Box was created. This is like a virtual machine which runs dos and do whatever the old dos was cabable of. It runs the old version games and allows you to control speed and even map the keyboard to the older keyboard layout as the new keyboard layout might nto work with some.