Noob question about power supplies
So I've been reading these forums nonstop for the past couple days and definately want to put a carputer in my ride. I'm a bit confused on the power supply situation. I've heard Opus is the best in terms of compatibility with a car, as in the computer won't restart during cranking. But I was thinking about using a power inverter for my car, so I can plug the computer, playstation, and maybe something else into one unit and because it's generally cheaper. My main question is, do I still need some sort of power supply for the computer so it will be able to be plugged in to a regular 3 prong outlet like the inverter will have? I know that when you build home computers you still need a power supply in them. So is that what the opus is, just a power supply for the computer so that is all you will need to plug it in to the car's wiring? And will I still need some other sort of cheap power supply in order to plug the computer into the 3-prong plug on the inverter because I got an inverter instead of Opus?