Xbox's work, but if want to benefit from GPS, internet, and mainly music rather than games, and movies a computer is a better choice. (now don't say an Xbox is a computer please

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Xbox costs:
~$150 for the xbox
~$50 for the chip
~$100 for a larger hard drive
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$300 for the xbox set up MINIMUM
Now, perhaps you have to have somebody do the modchip install for you, or you want a remote, or any other parts, that's more $$
Carputer costs:
~$150 for the motherboard
~$70 power supply
~$50 memory
~$100 for the harddrive
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$370 for the Carputer
More money for the Carputer itself, but it will run cooler than the modded xbox like ITinker said, more people know how to piece a computer together than mod an xbox and you can change or alter the Carputer easier than the xbox (ie: more things that can be different).
For roughly $70 I would rather have the ease of the computer for the internet, wireless, gps, sound, etc.