ok i have a logitech THX home theatre system, with the 400Watt sub, the fuse blew so now im just saving it for my car. the question is, would i be able to hook something mean for a computer up to a car?? the Sub box has a amp in it.
A horrible idea. Keep your computer speakers at your computer and get some real car audio stuff. If you absolutely have to do this (and have all your friends make fun of you ;)), JayJ is right, a power inverter will work. These can get a bit expensive. Make sure to spec the inverter such that its power matches the power requirements of your speakers (which can be pretty high). Overall, a really bad idea that will still cost you a pretty penny for a good inverter and won't sound nearly as good as the real deal.