" Close your eyes and enjoy your computer performance". But I think one thing could be missing, is the warning that using registry cleaners with a 'Closed eye attitude', can perhaps lead to further problems.
I would always suggest that whatever programme you use, make sure that you understand it before deleting anything from the registry ;o)
Would mention that I have used or still use some of those mentioned above and linked. All provided a good and free method, and are recommended by many.