I want to keep my system running ultra-smooth. That's primary. But I notice that people who know more about how to keep their systems smooth than I do sometimes install clear docks, themes, and the like. My question is this: what's OK to install if we want a nice clean system? Is Unsanity stuff OK? Are themes? TinkerTool? Or should we keep everything very Apple? Exactly what sorts of things shouldn't we mess with if we don't have to bother with a reinstall?