If they came in recordable sleeves, does that mean they were recorded off tv? Are there any interviews or trailers before the main feature plays? As long as you can tell us that, at least one of us should be able to figure out what you have and if it is worth your time to transfer them to dvd.

And do check if they're widescreen or pan/scan. Unless the VHS tapes say "Widescreen Edition" on the cover, it will most definitely be a pan/scan version.

Also, episode III was never released on VHS. So you'll never see an official VHS set of all three prequels anyways.