> So, I'm trying to mirror 220 URLs, and HTTrack gives me 
> the following error:
> A fatal error has occured
> assert failed (tempo)[sizeof(tempo)-1]=='
> in file 'C:\Dev\WinHTTrack\HTTrackInterface.c, line 251

This is a limit from the winhttrack GUI - put all your URLs 
in a text file and use the "URL list" feature ; it should 
do the trick (the text file should contains all URLs, one 
URL per line)