XGworks is a sequencer, like Cakewalk or Cubase, but specifically aimed at XG (such as you have in the 2100). It does all the things that other sequencers do, though the audio is very basic. Unlike other sequencers, however, XGworks has a style generator and auto arranger and will accept external styles such as those on your keyboard. The real bonus is the XG Editor which gives you full access to the synthesizer in your keyboard if you have the proper updates. The reason for updates is that XGworks for keyboards is poor as the program was really intended for stand alone XG synths. To this end I have done the updates I mentioned above, particularly as my 740 doesn't have the more advanced display of the 2100 and most of the synth features can only be used via sysex, hence XGworks which transmits the proper sysex in real time. You can get some details from www.yamaha.co.uk
which is the only place you can order it from if you're not in the US.