There is a trilogy of books called the Jedi Academy set ten years after Return of the Jedi. In that book a Sith spirit tries to seduce some of Luke's new Jedi. I am not sure if this has any relevance to the beginnings of the Sith or if Lucas supports this book at all but it was still a pretty good series.
Stephen Kuhn
Prism Network, Inc.
System Developer
At last we can reveal ourselves to the Jedi.
At last we will have revenge.
-Darth Maul