I agree with those of you that favor the use of CCleaner. I use it before creating a backup image so if I need the image I don't get the ... well you know.
However I have never felt the need to clean the registry with anything. From all I've read it really doesn't make any difference to Windows 7 operation unless you take out something that Windows is fond of, but that's another story.
I'm still using an older version as I don't like the new flat interface nor do I need any of the new improvements. It ain't broke so I can't see trying to fix it.