I have a small laptop that I only need occassionally when I travel. Would like to get some more value out of it by using it as a digital picture frame when I'm in the office. However, the Google Picassa and Windows 7 photo screensavers rotate pictures way too fast. I'd like the picture to change once every 15+ minutes or so. Does anyone know a good, free, and lightweight application that does this? I don't need it to play music or come with any special transition effects, but its ok if the app has those features. Thanks!!