Hi I am using an M1-ATX 90w power supply in my VR to power my in car pc. Some useful info where I got mine at Linitx . The benefits of it are it does not leave your pc on all the time, thus draining your battery, it can be set to shut down your pc a certain amount of time after your ignition has been turned off. It also detects load on your battery and shuts down the pc before your battery gets too low to start your car. I have no problems with this unit, recomended, not sure how you would interface it with an xbox tho, you using it for games or audio / video.
