Or your enemy?  I work with a lot of CMS ’cause my clients work with a lot of developers.  And I have learned to hate some of them (the CMS not the clients or the developers).  I hate systems that insert garbage into the URLs and then don’t allow us to rewrite the garbage into something appealing to search engines and people.   I hate systems that don’t allow us to see the code and manage the code on our own pages.  I hate systems that make it impossible to move a website to any other hosting or CMS environment (and that’s a lot of them).

Ian Lurie recently posted about SEO-ready CMS, and there’s some good points in it if you are looking for a new system (or building a new website).  A system I have enjoyed on several small business sites is the fck editor, which I first learned about from Synthetic Kit.  This is a flexible and intuitive system that does not require any installation on the client computer–it will remind you of working with Word (only fewer crashes).  I’ve also run across it in sites built by Dennis Clevenger over at CleverConcepts, and it seems it can be installed in different versions that offer the feature set you need (but ask Dennis about that).