I am working on a Compaq Presario dinosaur for a friend and decided that the best thing to do would be to upgrade the motherboard and processor. The motherboard looks like an ATX, but I know that Compaq and HP used to make their cases proprietary so that you had to replace it with their components. Has anyone tried to put a new motherboard in a Presario 5600 and if so, any thoughts on MB size or particular model? Thanks.