> What I was trying to do is what is explained in this
> HTTracks FAQ:
> <http://www.httrack.com/html/faq.html#QM11c>
HTTrack will convert all file:// links to relative ones. 
what part of ALL didn't you understand.
> 
> copied. But updating it will rewrite all files, even
> files that haven't been changed... and writing to an
> usbdisk can take a long time.
There's no way for it to know whether it's changed or not.
my solution only write to usb those files with newer time than what's on the
usb:
1) get touch.exe from <http://sourceforge.net/projects/unxutils/files/>
2) create a batch file to change the new file's timestamps to the original's
(untested)
rem newDir origDIR
setlocal disableDelayedExpansion||pause
for %%F in (%1) do set new=%%~dpnF
for %%F in (%2) do set orig=%%~dpnF
for /R %%F in ("%new%\*) do (
   filenew="%%F"
   fileorg=!filenew:%new%=%orig%!
   touch -R !fileorg! !filenew!
)
3) xcopy /S /D newDIR USB:

for /R