Thank you for your reply, 

but the site is not down. "category" was my typo - sorry for that. The correct
link is <http://wl4.wealth-lab.com/cgi-bin/WealthLab.DLL/categories> and this is
what I used in httrack.

I can download a lot of links and pages from that site, but not the threads of
the discussion forum.

Why not?