I heard somewhere that the aluminum powerbooks with superdrives support rewriteable DVDs....I'm sure sure that they're DVD-RW format or not, but I'm guessing they are. Do the desktops support this? Reason being, I intend to do a lot of DVD backups, and I'm into film, and I don't want to waste $5 a pop on a DVD every time I do a backup. Has anyone verified this?