Creating a self overwriting partition/folder.

I'm not aware of a way to do this automatically when a drive gets full.

You could have a cleanup run that removed the oldest files once a day or so, but that's about as close to what you are asking that I can think of.

There are lots of ways to do that, but a quick google search pulled up this link.

http://stackoverflow.com/questions/51054/batch-file-to-...

If you get that setup the way you want it, just add it to task scheduler at the intervals you want it to run and that should do it.