If you have some soldering skills, just toss everything on jamma fingerboards, mount your stuff and you're gold. I have PC, 360, DC and PS2 wired on JAMMA fingerboards mounted neatly on 1/4in plywood and can swap systems into any cab just like any other pcb with no effort. All those systems can use the native VGA output to directly drive the video making it easy, but I added 15k RGB out to some as well. Component audio is cake since they all obviously support it too. Cost is minimal, just have to buy pads to hack and fingerboards from either Bob Roberts or jammabaords.com. You may need a tiny 5watt amp to drive audio if your cab does not have one.
Ipac seems to be the way to do it if you don't want to get your hands dirty but you have to buy all these separate cables and adapters and still need to install the thing, seems just as difficult to me.