Well lets see here if i can stir things up a little...LOL Anyways why we argue this point is beyond me. An opus is like $200 and last i looked the inverter and power controler on the carpcstore site is like $125. Add the cost of a PSU if you dont have one and viola youre over $200. (And if you tell me you can get a good switchable PSU for $75 please slap yourself so i dont have to come do it for you.)
Now as i see it anyone planning on building a powerful PC wont mind the extra cost of controler, PSU, and inverter. But those looking at the epia type boards or something similar (micro atx) would be better off with the OPUS.
And anyone seriously interested in this hobby would be better off with a sproggy or mastero DIY. If nothing else for the learning experience. (You will need it later as your imagination and confidence kick in).
Over powering either inverter, OPUS, or any other solution will eventually kill it. And i may have missed something but what happened to the Keypower in this discussion or the Aries? They would both work great with a powercontroler that kyle has mentioned. But then again you are over $200 bucks in combined expense.
So as i see it anyone trying to find a cheap solution for powering a carPC needs to think twice. Cheap out on something esle like the 3rd or 4th useless never used monitor and spend some cheese on your power setup. All that fancy **** dont mean a thing if it fries or freezes up and crashes.
EDIT > Forget to mention someting. I am strongly in support of flaming and buring on this forum.