Can't remember which, but one of this months Computer Magazines tested several registry cleaners and other programs for speeding up your computer.
They tested them on an old computer, a not so old computer and a new one. Very few of them did anything other than very marginally increase speed. The increase was only measurable using lab techniques and it would not be noticeable to most people.
Keep your money in your pocket. Admittedly I still use the free Ccleaner.