For cleaning the registry itself I generally use RegCleaner or RegSeeker since those are a little more advanced there. RegCleaner opens up to a main window showing all non MS programs installed and can even be used to spot adwares since you either see new or old next to each main reg key.
When something is left in there by an uninstaller you'll know with one look. It also has an automatic registry cleanup tool. That can hamper a fresh install at times when something is still left there.
http://www.dewassoc.com/support/useful/regcleaner.htm
RegSeeker is a slightly different kind of registry tool besides a cleaner since it can locate and remove one specific value you know and even drivers by name from the system32 foilder in the Windows directory.
http://www.hoverdesk.net/freeware.htm
The main problem seen there is no "for anyone" option for general application. By having it installed for one user it becomes unavailable to other user accounts other then the user specified. The software writers assume there is only one administrator.