Plone
Installed Plone today on my WinXp Pro machine at home. I was already using port 80 for Sambar and port 81 for IIS. So, I had to use port 82. It is working fine. It seems to be really powerful and has a lot of features. But I am not really sure how useful it will be. The greatest drawback is that you need admin rights to your own machine. For people who just have webspace with hosting companies (and not admin rights), they will not be able to use Plone. I feel that MovableType is much better (I am using it for this blog). Also, you might want to try put PHPNuke.
I might be wrong about Plone though. Right now, I have not figured out a way to keep the contents on a remote server. Comments/ suggestions are welcome.
I know that the UTK-SIS website uses Plone. That's where I came to know about it.
I love Plone and Zope combination which I have powering my website at www.sebpayne.com. Many companies will provide you with Plone hosting (already setup) on a server. http://www.objectis.org/english offer free hosting with a preconfigured Plone server. I'd give it a go.
Seb