Hmm .. if you want to make a full backup, use the backup scheduler and push the files on the 321.
You could also make your files on the 323 accessible via FTP (do NOT forward the FTP server on the internet while you do this) and simply "download" them from your 321.
If the 321 also supports FunPlug, set up a Sync server on the 323 and the client on the 321.
//HSishi