Welcome to the forum! I think you could get away with the usb/dc-dc power supply http://store.mp3car.com/Mini_Box_DCD..._p/pwr-052.htm That should do the job for you and give you the auto-start auto-shutdown. I think I might go with a SSD just to somewhat compensate the slow processor. Which you could use should you decide to upgrade the hardware at a later date. I guess you need to make sure that computer has sata before ordering one. Good luck and don't forget to start a worklog of your progress. SNO
Pictures might help with identifying your mainboard or computer!