DC>AC power converter from the outlet powering a quiet (quieter than the one in the tooth) ATX powersupply. I didn't think about the uninterupted power for the computer during start/stop so good call on that one. i supposed a UPS work just fine.

My question is which ATX power supply will be the best, providing 150 without making much noise doing it. In fact, the car is quiet so a quiet power supply is a must (its an SUV so trunk install isn't an option)