I dont think you need that CarPC Pro V2.4 Advanced ATX Power Controller. The Opus should have all that stuff built into it such as shutdown timers and hookups to the ignition.
If someone more experienced than I would care to interject id be more than happy to learn the facts, but thats what I understand them to be. Also, if that Xenarc cable is that came as a regula VGA cable you might be able to go to a local PC store and get a bunch for cheaper, maybe not but its worth a shot. Oh and that Toshiba CD/DVD you can get from NewEgg for $43 instead of $58 See, look at me already saving you money
Other than that, looks good to me (but what the heck do i know??)