Really? cool!
I guess Beatmania is the original game, what I was thinking of is a prog called BM98, which I guess is a one-game-only emulator for beatmania. It runs well on win95 and win98, but dunno about xp.
By the way, my friend who got me into beatmania showed me a newer version of BM98 called Mixwaver. (there's a Mixwaver II out now too) It plays all the same files, but runs better in winXP and has nicer features, like two turntable keys for lefties/righties, and is able to sort its song list by many different criteria. The new one runs great on a cab, if you have buttons for the space bar and enter keys.