Content Management Systems

Hey all - I was hoping that I could get some advice! I am setting up a site that will be quazi-portal-ish in nature. As such, a lot of different people in a lot of different departments will be making contributions and editing parts of the site. I have never done something like this before, but I think what I am looking for is a content management system (CMS). Is this correct? I have been looking at a bunch of the packages from the list on HotScripts, and I have to admit I am overwhelmed and confused. It seems that packages such as Midgard, Typo3, etc. would need to be set up by the server admin.. This will not work for my situation. I am looking for a system that: 1. Allows multiple users. 2. Gives me complete design control. 3. Has a non-HTML editor interface (my clients are not so savvy), and 4. Can run just off of a PHP/MySQL interface that I can setup without access to anything but my server space and database. Does anyone have any suggestions? Thanks a bunch - you guys are the best!