How to get difference beetwen revisions

[JBB]

I'd like to get the difference beetwen two revisions of a folder (know
which files changes)
And this without checking it out.
I just want to export files that have changed.

In Eclipse it'a easy to get differences between two revisions, but you
can't then export only these files.
So I decide to make a litlle python script that do it for me.
Up to now I do a 'checkout', then a 'log' on each file, parse the log
to see if the file changed beetwen my two revision, and then remove all
inchanged files.  But this is very long because of the number of
(inchanged) files and their size.
I'm sure the cvs server could do some thing for me. Maybe whith the
'diff' command?

Thanks