You are much better off with a series of bike batteries then one car one, they will hold more charge for longer per same area, plus you are talking 600 watts out of those, thats a lot of current to be running. Inverter is a splendid but wasteful idea, it is very much not efficient, and you'd be wasting all that precious electricity, however i can't also imagine anyone building a transformer for a motherboard at their home convenience without a degree in electronics. So I would suggest scrapping the idea with using a conventional mobo and do something crazy, like we always do. choice #1, you could build it using an X-Box, however the power converter is still inside i beleive so it is not such a great idea, but saves space. Choice #2 building it out of a linksys router, and yes there is a project that is doing just that, now that should solve some problems, i beleive that that box has an external power supply, which means bingo for you, it will be pretty easy to buid a transoformer that converts DC into variable DC, square wave, and really high frequency, then pass that through a transformer to get the right voltage, and add a diode bridge, some resistors, and a few capacitors just in case, check to make sure you got the specs on the power supply right, the specs outlined on the linksys's power supply, and you are good, all you have to do is hook up positive and negative to the original power supply wire and plug it into your linksys router/Linux box, little space, and you have a Debian box to carry around with you
----------------
Microsoft, the leader in using innovative tactics to promote irksome experience, coupled with antiquated technology that's held together by a pyramid of makeshift afterthoughts.
Apple, the leader in using irksome tactics to promote innovative experience, coupled with an antiquated core that's enhanced by state-of-the-art afterthoughts.
Linux, the leader in not using any tactics to promote user-defined experience, coupled with state-of-the-art core enhanced by innovative afterthoughts.
