NT Registry Optimizer (NTREGOPT):
May not be totally safe, the reason I say that is because after using it I noticed some special links like those that use a CLSID for the link, I suppose that's what there're using where dead in my "Start Menu\Programs\Administrative Tools" and "Start Menu\Programs\Accessories\System Tools" and weren't at all easy to fix since System Restore didn't help at all, nor did the backup created by ERUNT. I've since removed NTREGOPT and am using
RegCompact.NET.
RegSeeker:
Remember it's a beta versoin, and it acts like beta software in many instances and can be unpredictable from what is listed to what is actually removed from the registry. Unless you have an insanely huge exclude.ini file I don't see it as being all that safe to use, just search the CCleaner forum for RegSeeker and you'll see what I mean. It has the ability to mess up the installation of Windows Media Player, ZoneAlarm TrueVector Service, and it can drop kick MS Office right in the balls, etc., the list goes on and on. I still use it even though I'm critical of it, however I look at the undo file(s) it creates.