>      Are there any possibility to download only files 
that 
> are not saved in local directory (the local direcotry 
> replicates partial site structure) ?
If the partial content was created by httrack (that is, 
with a valid cache), this should do the trick. If not, 
httrack will attempt not to download twice "data" files 
(html files will be retransfered) if found on the same 
expected place. This might work, depending on the local 
file location and on the remote server responses (generally 
httrack will ask the remote server to complete the local 
file, and the remote server is supposed to reply "no more 
data")