SpamAssassin Help

We are having big problems with spam. I recently implemented the SpamHaus.org RBL and I would say we've seen roughly a 20% decrease in volume. We are really looking for somewhere around 80%. I recently setup a SuSe 9 box and downloaded SpamAssassin. The plan is to set this box up as a gateway to our email server. The email server is a Windows2K box and we are running Communigate Pro as our mail server. The problem is, I'm not extremely familiar with Linux, and all the documentation I've found on SpamAssassin has been very unreadable to me because of my Linux illiteracy. Does anyone know of documentation on configuring SpamAssassin that is a little more friendly to those of us who don't know Unix so well? Thanks.