I use it all the time to clean up after a USB DEvice fails to enumerate or enumerates incorrectly. Every time you change something about a device, new registry entries get made.
Before jumping in, you might wish to learn something about that which you want to mess with.
Google "windows registry" and explore some of the many links that come up, like this one - http://support.microsoft.com/kb/256986. Lots of reading is recommended.
Details are different depending on your OS, so have some background to that specific one you're about to explore. You may still be able to find a utility, Registry Enumerator, which can find linked registry entries.