LightingLEDs or Cathodes are great for the heat factor, the ease of installation and they never have to be changed out again for the life of the arcade (unlike a florescent bulb). To siphon off the PC power, I wanted to avoid splicing into my power supply directly, so I purchased this adapter which worked out well:
http://www.xoxide.com/pci-power-bracket1.htmlThen I used a spare molex Y splitter I had lying around the house and spliced into that instead. Then after the splice was done, I simply plugged it into the connector on the outside of the case. This works very well if you ever want to work on the PC and remove it from the arcade unit. You don't have to worry about cutting your splices that are going directly to the Power supply. You simply disconnect it from the back.
SoundActually the ohm thing is very simple - also known as speaker impedance. Just make sure the ohms match. For example, in car stereo speakers descriptions it will usually note if they are 4 ohm. The same goes for computer speakers which should also be 4 ohm. Then simply splice the wire (take the computer speaker itself apart and then disconnect the wires for the speakers and wire them up to the 4 ohm car stereo speakers. Mixing differents ohms is a no no. 4 ohms require more power (lower number means higher resistance) so connecting them to 8 ohm devices or vice versa will either kill the speakers or the amp in the system (over time of course).
Power SwitchAssuming it's a fairly new form factor computer, I believe you can only use the momentary push button to power it up or shut it down. Usually ATX type motherboards have this. You can tell what kind of button you have by the sound of it when you press it. If it's a momentary push button, you don't hear anything when you press the power button. If it's not, you will hear a "clicking" toggle switch and the button will stay in when pressed. If pressed again, it will click and then pop back out. Based on this info, if you use a normal switch on an ATX motherboard it will simulate the button as if you are holding down the power button since it will always be making a constant closed connection to the motherboard.
As far as DOS goes, it will still shut down just fine. Again, the issue is really what form factor your motherboard is and what type of switch is already there.
~ DeLuSioNaL