i know somebody on here hooked up their xbox to their head unit. not sure what head unit they had, but i think the main problem is the power supply, video game systems draw crazy amounts of power, youll have to solve the power problem.
And while we are at it, take the number of Watts that you need to provide for the system and divide it by 10. That will tell you about how many Amps you will draw from the electrical system (alternator when the car is running, battery when it is not). Note that most car batteries will go flat pretty quickly when drawing more than about 15 or 20 Amps (150 - 200 Watts). You're not going to want to be gaming for very long with the engine off.If you are going to run an XBOX360 or a PS3 in your vehicle, dont buy anything smaller than a good 400W power inverter. You will destroy anything smaller than that and possibly screw up your gaming console too. Get a 500-800W inverter if you can and use at least 8 gauge wire directly to the battery for power. 4 gauge is better if you can swing it.