Regcleaner is a freeware registry cleaner, that does a better job than Microsoft's RegClean, when the developers follow the rules.

When you double click the Regcleaner.exe, it will unzip 4 files. You MUST read the Readme.txt and Optimize.txt files.

NOTE: A few users have reported that Regcleaner works in Windows 2000. There certainly isn't any reason why it wouldn't, but I haven't tried it.