I have recorded several movies onto DVD-Rs using my Panasonic DVD recorder, but I've become worried about the uncertain lifespan of burnable DVDs. I would to be able to transfer some of these files to my big external hard drive, then re-burn them to fresh DVD-Rs when/if necessary. But I only have a Mini with a combo drive. Is is possible to have a Superdrive or other aftermarket DVD burner installed in this thing, and if so how much would it cost?