Is it better to download movies + buy mem sticks or buy the umd version [psp]?

buying a memory stick is a whole lot better because when your done with a movie you can just delete from the memory stick although its more expensive at first it will be cheaper in the end you can go to the web site www.pspiso.com where you can download a ton of psp movies and t.v. shows already in the correct format for your psp