Looking for a MIDI file player that is capable of live mixing/blending, in the same way that a DJ would operate a pair of turntables, or Traktor software etc. There are squillions of jukebox style MIDI players of course. But specifically I'm looking for the ability to cue, beatmatch and blend files on the fly.

OS requirements are flexible. DOS or Win9x would be cool, but XP is ok. I've already had early versions of Ableton suggested. I wouldn't mind something lighter than that, and besides, that seems impossible to find.

Any suggestions?