Downloading new files but leaving out the old...

[mgolden]

For downloading, how would I set this up so that I can download files from one site but filter it so that it only downloads files that have not been downloaded before. If they have already been downloaded I need the program to ignore those files. I'm downloading from a root directory and the files I download stay in the list of available files for a week if not more which is why I need to ignore the previously downloaded files to avoid duplicates. I want to make sure I have this set up correctly. Is there a way to do this in the site advanced settings?