http://www.majorgeeks.com/Lexun_RegScrubXP_d2048.html
I typed Lexicon. I was thinking funny. I meant Lexun

Also, WinPatrol and Spybot Search and Destroy's Tea Timer offer registry change protection.

That is- if something tries to change your registry or add itself to your Start up list- they alert you to it first.

When in doubt- DENY!

On Major Geeks, you can also find HDCleaner- I use- prefer it to C Cleaner.
It comes in German, but an english version is available.
It has some really great controls, options, features and anti-spy tweaks.
like Spybot S&D it offers a file shredder too.

All of these are free.
No I don't work for the company.