BRUCE_Y There are some maintenance and settings utilities which are free (TinkerTool, Onyx, others), and some which charge a small shareware fee (TinkerTool System, Cocktail, Panther/Tiger Cache Cleaner, MacPilot, others).
Many have some overlap of features, but no one tool does every single thing (that I have found), so I use a combination of several ( and I have registered several).
(caveat: above is not a complete list - I did create a list of utils and features and posted it someplace a month or two ago ... now where did I do that ...)
(Version 2.0.3)