Lori, I don't know of anything like napster but you can try download.com .
http://download.cnet.com/
I ran a search for educational freeware and came up with this. There is some pre-K software. Do a few searches and you will probably find plenty to download.
http://download.cnet.com/1,10150,0-1...=2&dlsize=&ca=
This is a great idea. I am somewhat new at burning cd's but I had not thought of doing games and such for the kids. Great idea. Let me know how it works. I might try one too!