A last remark: httrack will, by default, limit the total 
bandwidth to 25KB/s, to avoid any overload. If you CAN (I 
mean, you are authorized) to crawl a site at a faster rate 
without putting it on its knees, you can upper this limit 
in the httrack options, or even getting rid of it.

BUT do not use T3-like connections on a single site, or you 
will create a denial of service problem (and you will 
probably force the webmaster to report the abuse, and/or to 
ban all offline browsers, which will be bad for other users)