running dos base programs in win 2k pro

I have a client that has an old database program that only runs on machines with win98 or win95. But they just got a machine with win2k pro and it wont let me run the program on it. keeps telling me to try a forcedos command and see if that will let it run. but it doesnt. Can anyone help me is there some kind of program that will let me run dos based programs in win2k pro? If there is please let me know asap.

ps
I thought about doing a duo boot but it would be to hard for them to grasp the conscept of that so you can cancel that.