File extensions that should never be deleted

Does anyone know where I can find a list of file extensions that should never be deleted ? I am trying to clean my 60 gig XP
hard drive and want to exclude anything that could be harmful before I run a scan for duplicates and other waste that can
be deleted since finding over 12,000 duplicate files. Any other advice would also be appreciated on this massive cleanup.

Thanks, Bob

mmm,

I foudn the following about protected files.

Protected File List

WFP protects files with the following extensions that are installed by Windows: .dll, .exe, .ocx, and .sys. In addition, the TrueType fonts Micross.ttf, Tahoma.ttf, and Tahomabd.ttf are also protected.


At the end of the Windows installation, WFP runs a scan of all protected files to ensure they have not been modified by applications installed through unattended installation. WFP also copies verified versions of these system files to the cache directory. When an application attempts to replace a protected file, WFP can restore the original file from the cache directory.

To specify the location of the cache, use the following registry setting.
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With deleting duplicate files, you really have to be careful. If anyone cares to add anything else to this, I'm listening.
Welcome to TZ by the way!
:D

Thanks, I appreciate the help. I have been looking for good duplicate file cleaner (possibly with fuzzy logic) that would know which files to exclude but with no luck, although I've checked a lot of programs and done a thorough search. Any suggestions?
Thanks for the welcome, I'm with a couple other sites but get to much "reinstall or copy and spend days deleting then reinstalling again". I think thinking and learning are out of style. Did your registry setting disappear or am I missing something?
Cynical Bob

Perhaps one of these will help you out:

- System Mechanic
- DeDupe

Not sure if they have the features you are looking for. I haven't tested either of them yet.