Disklavier

I have a Mark III and would like to connect it to my computer. I have 
so many midi files now that it makes more sense to play them from a PC 
than floppies.
The manual has some information but I am still not sure where to start.
Has anyone done this and if so do you have instruction on how to do it.
Do I need additional software on my PC? Where can I get a cable? ECT.

Thanks for the Help.

Alan