> I want to mirror a large site.  I already have a mirror
> started with another program; the file structure is
> identical to what HTTrack would use, only there is no
> hts-cache, of course.
> 
> If I use HTTrack with this, will HTTrack 'detect' the
> already-existing files when it goes to download a file, or
> will it just blindly overwrite the already-existing
> identical files?
Yes - I will implement a hack in the next release for such 
cases (activated with "update hack") that will normally do 
the request remotely, and break the connection if the local 
file size is identical to the remote one, EVEN without any 
cache.

I can send you the patch, if you want.