Registry First Aid is a solid registry cleaner that many PC users swear by. And I received news today that version 6 has been released, with some important new features. Here's the major changes in this version:

• Vista compatibility:
support running in a least privileged environment;
support of Vista registry;

• display snapshot descriptions in registry snapshot lists;

• new and improved algorithms giving more thorough searches,
faster working, and greater reliability;

• filtering and sorting found registry entries;

• option to scan for errors all user registry hives is available under
full administrator only;

New users can download a free trial to get started here: Registry First Aid Trial

Existing users can download an upgrade for the software here: Registry First Aid Upgrades