I don’t think I could survive without Reg Cleaner. Unfortunately, the guy who made it has upgraded the software and is now charging. The site at the link still let you download the older version for free.
Basically, if you’re less than a pro, reg cleaner let’s you do things in the registry of Windows, without risk. Whatever you do, will create a backup (as opposed to RegEdit), so if you screw up, you can always go back.
Reg Cleaner looks for orhaned registry entries, let you see what’s starting up through the registry (not the start up folder) and is a good way of cleaning the computer after you’ve un-installed some software or deleted some files. I run it at least every week, and it has helped me get rid of some pesky stuff that ad-aware and spybot couldn’t handle.