Hi SLF,
Microsoft had a utility called "regclean" which did exactly what it says on the tin... nearly. Unfortunately it was never really taken to product strength and I think MS got bored with complaints of trashed registry databases and pulled it.
There are some third party ones out there... must admit to never having used them myself though, so it really is a case of "caveat downloader"
Here are a few:
WinSite Windows Registry Tools
Hope that helps...