This is what they make the help files for! Seriously, I don''t mean that to be wise, but these are all explained in the help. The edition of MSDN that comes with VC++ 6.0 and the updates for a few years after have this info.

You can try searching msdn.microsoft.com but you''ll have to weed through tons of .NET stuff and bad links to find the info.

The .PLG files are just HTML formatted logs (that''s why they have the IE icon) so you can dump them if you don''t want to save a log of the last build.

The .NCB caches info for some of the IDE things like ClassView. It''s safe to delete and you definitely don''t want to back it up since it contains some hardcoded paths that''ll seriously screw things up if you open the project on a different PC or in a different path.

I think the .APS is associated with resource editing. I''m not sure what happens if you don''t have it since, for some reason, it seems to rarely appear in my projects (MFC only?). I *think* I''ve gotten away without having it.

The .OPT stores things like workspace options, things like open files that are auto-reopened, I believe. I think the debug paths are stored in here too. If you delete it, you simply lose these settings. I believe Microsoft recommends not backing it up or sharing it since there is path info included but I sometimes do anyway since it contains some useful settings.

I think VC++ will regenerate the .CLW file but it pops up a scary message box when it does so I usually keep this one around.

I''ve gotten away with no problems just backing up the source, project file and workspace file. The others are generated by MSVC when you make changes, compile, load the project for the first time, etc. I''m pretty sure they are just there to streamline certain processes.