Disklavier

Hi,
Just got a new Yamaha DGC1 (Mark III) delivered and wondering what are 
some of the favorite software of other users? Where is the cheapest 
source for software? Also, anyone have the Elton John Greatest Hits 
1970-2002 companion diskett to the audio disc (I currently own)? How 
do these or any types of this disc like these sound? I also posted 
this in another forum to generate a variety of response. Thanks for 
your assistance ahead of time. Sam