Shim,
I agree with Rikki...I have done this and it is not a good solution because the Yamaha PSR's do not have a very good MIDI implementation. On reason I went Korg is that in any track you can have a user voice that sends out Bank/Program change to select the sound correcly on a sound module or softsynth. However, it still is mot a master MIDI controller you need to take full advantage of external sounds. AND remember..the Yamaha styles use a lot of mega-voice...and no VSti or sound module that I know of support it. AND you need full XG sound set to support the styles unless you want to go to each one and re-program the sounds on every track.

You can make it work but I think you will be not very happy.

Maybe get a used T2, T3 (new or used these days)? or even a T4.
If it were me and I wanted to stay Yamaha, and be economical...I would do a deal on a T3.

Lee S.