I finally have SpamAssassin
working on my Windows server. It's actually really good at catching spam. Once in a while one slips through, but for the most part it's made my email more useful. I thought I'd share the solution in case anyone else wants to do it.
Here's what you need to mirror my setup:
You just install the Outlook plugineven if you don't have Outlook on the server. And then add an entry that calls the WSH script to any tab file in the Xmail filters folder. I have more detailed instructions in the WSH file. Just want to share the spam-filtering goodness!