hi looking for a program to sync and a bit more

happy Friday afternoon all (or morning pending on where you are in the world)

I wanted some advice please (hope this is the right place to post this)

I am looking for a program. What i want it do do is basically sync folders to an external harddrive BUT. say for instance I dowlnload a movie at the mo i put it on 2 external drives

1 goes on a 1TB external drive (ntfs)
and the other on a 320gb drive (fat32) I use this one to carry films with me and to put on my ps3.

Now the small one is getting full up and i have started to delete movies i have watched.

what would be nice if i just put them all in the small one then when i sync it to the big one it only adds what it doesnt have already and NOT delete off whats already there.

Does that make sense?

and is there a program that can do this.

hope you all have a good weekend

I think I understand.
Can you not just drag everything over, and when you get the alert saying a file is already present, just press no to the copy prompt, or choose "No to all"

thats a good idea I suppose but I just wondered it there was something that would automatically do it so i didnt have to bother (lazy old me)

I have NTI shadow as my back up so everytime i make a change it automatically backs up the modified file.

I kinda wanted something along them lines but for file transfers