CCleaner (Orginally Crap Cleaner) is an inuitive program that removes programs, intelligently deletes unused registry values, and also clean the cache and other unused data of programs like firefox and explorer. Make sure you create a back-up of the registry when it asks you, though.
Although I don't mean to imply that it isn't an effective registry cleaner... I, brash as can be, never back up the registry when it asks me too.. and I haven't ran into a problem.
There's also a portable version floating around the internet, if you can find it.
Bookmarks