Well, what about an old G4, eBay has a bunch, and theres always a possability apple stores around might have a few, they are trying to get off the shelves for new G5s... If you were able to rig up a new box (wood/enamel/ect.) And connect the screens to it, you should be able to get a reasionable videocard, that will run 3 screens.... How much space for this laptop-desktop-lcd item are you looking at (physical) and is it really just to run pictures? because it might take you 1000 bucks... thats a lot for 3 pictures/frames... is this going to sit on a table, on a desk, in some shelves, or maybe mounted into the wall?

-Knife