I'm still sorta new to ipod and itunes and I need help understanding how to download podcasts.

So I have a bunch of podcast subscriptions a I just came to the realization that you can expact the pocast tree and download all the idividual episode. But it seams like Itunes will only automaticly download the latest one. And alot of them have close to 100 episodes.

It's there a way to just have itunes download one unwatched episode as long as I don't already have an unwatched episode?

So if there are a 100 old episodes it will download just one and keep it until I watched it and once itunes knows that I watched it, download the next old episode automaticly?