The biggest problem I had was figuring out what the PDC (primary domain controller) was for my domain. But, I went to a Windows machine (and typed set at the command line) and it gave me the LOGONSERVER environment variable that I needed (which worked).
I also found this page:
http://sivel.net/2007/05/sso-apache-ad-1 which gives a super easy, step-by-step how-to.
One side note: My network does not actually use PDCs (I guess that is sooo NT 4.0 ??) and instead uses Active Directory. But everything still worked just fine.
I have to admit, this was MUCH easier to set up than I thought it was going to be! Thanks again for the help.