Registry Cleaner of PC Tools
In this PC Tools Registry Mechanic 2011 review, I allowed it to scan the computer's registry for errors. I have compared a registry cleaner program for Windows XP and a registry cleaning program for Windows 7, which I find not all registry cleaners are recommended to keep.
PC Tools Registry Mechanic was right on every detected missing and invalid registry keys on the test system that has not received any cleaning by other registry cleaner. By locating each detected entry in the computer and by using the registry editor, I confirmed that Registry Mechanic did not find incorrect registry entries that required fixing.
The ability of Registry Mechanic to detect what it should detect is impressive. The bonus is that it will create a system restore point in case the user wants to restore the fixed items. Like other good registry cleaning software, Registry Mechanic allows you to view the paths of detected entry (location of the registry and file) that many registry cleaning programs will not display unless it's freeware or a registered version.
Compacting the Registry Using Registry Mechanic
One of the neat features in Registry Mechanic is the ability to defrag Windows registry. When I tried this feature, it properly displayed how much wasted space that my uncleaned computer registry actually has:

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Using
PowerTools Lite, it did report the same on the status of the registry in Windows which is good news because two different reputable programs have reported the same result.
Please read the review on PC Tools Privacy Guardian for information on performance in Windows. The disk and browser cleaning features in Registry Mechanic is exactly the same as what you get in Privacy Guardian.