I do not recommend any type of registry cleaner. I have a neighbor that try these programs. I had to reinstall the OS a few times for her because of their use.
With that said; only one I have is the one that comes with CCleaner.
On the forms, I have seen that a lot of users have have reported problems with the use of registry cleaners.
I have had Uniblue registry booster for a while when I was on Vista. I recently upgraded to Windows 7, and am now being bombarded with a hard sell on Registry Mechanic which I assume was part of the Windows 7 installation. I was happy with RegBooster, but am concerned that when it reports 2 errors, the RegMechanic insists I have over 1500 errors. Since both programs have been recommended in different threads, I am very confused! I am using an HP Paviliondv2000 laptop.