from my own personal experiences the basic thing i did not want when building my cabinet was 2 or 3 on switches.
this is how i did mine. i got a good power strip, wired an ac outlet to plug the power strip in to the 110 on / off switch on the side of my cabinet, that went to the existing cabinet power cord.
then, with any atx, or atx-2 style computer power supply, you only need to connect the green wire to any of the black wires also on the atx connector, to get rid of the soft off feature.
so, cut the green wire, stick it through a crimp on style TAP, and tap it into one of the many black wires.
you now have an always on power supply that you can just plug into the power strip, along with your monitor, speakers, etc. that is just one way to do it.
the second way that i have found and since upgraded my system to do, is to also still have computer control at shutdown, as well, where when you shut down the computer it also shuts off the monitor, speakers, marquee, and everything else in your cabinet. etc.
There are also two ways to do this too. one is to get an intelligent power strip. An intelligent power strip monitors the on or off state of the device that is plugged into its control outlet and thus also shuts off or turns on everything else connected to the power strip depending on the on/off state of the control device. This is the easiest, and also the most expensive way to achieve a total cabinet shutdown that is computer controlled.
the way i did it and for me the cheaper and more fun way is to hook up a reguar power strip to the cabinet power cord with a relay socket in between. then, all you need to do is plug in a 120v relay that has a 12v coil in the socket.
the 120 side is just a simple in/out, on/off setup. you want it so when the relay sees the 12v on signal then the 120 on the secondaries gets connected.
so then all you have to do is to hook a yellow and a black wire from one of the disk drive connectors, to the 12v primary sides of the relay. when 12 is on the primary, 120 is energized and will power all the rest of whatever is in your cabinet.
when you tell the computer to shutdown and it does, the 12v signal goes away and the relay opens and also shuts off all of your 120 volt stuff in the cabinet.
I hope this helps the question a bit.