REgistry Editor

Registry editor is an advanced tool for viewing and changing settings in your system registry, which contains information about how your computer runs. Windows stores its configuration information in a database (the registry) that is organized in a tree format. Although registry editor enables you to inspect and modify the registry, normally you do not need to do so, and making incorrect changes can break your system. An advanced user who is prepared to both edit and restore the registry can safely use registry editor for such tasks as eliminating duplicate entries or deleting entries for programs that have been uninstalled or deleted.

[url="http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/regedit_overview.mspx?mfr=true"]more about registry editor[/url]