Hello, a few day ago I installed Ms ISA server in my 
intranet were I works, so because ISA uses NTLM 
authentication HTTrack ´can´t work with the error 
¨authentication requiered¨, I found in the web how to pass 
the NTLM authentication:
there is a program named 'NTLM Authorization Proxy Server'
that works very well, here the explanation to install:

1) download the program code from 
<http://www.geocities.com/rozmanov/ntlm/>
the code is write in phyton so you have to download Python 
language interpreter version from  www.python.org. 
in the page of the program are a very good explanation, 
please read.

2) In HTTtrack you must configure the Proxy:
Proxy: localhost
Port 5865 
uncheck the option ¨usa proxy for ftp transfers¨ because in 
my machine don´t work.

Please, if you have any question follow the links and read 
all the information.
And remember that if you have a program that don´t support 
NTLM authentication the solution is the same as you read 
here, now I can usa Bitorrent p2p program with Isa server.
And sorry for my poor english.
Victor