I saw your Pop'n music setup before i started, thats very cool. im going to have to mirror what you've done.
But I as far as Guitarfreaks/drummania is conserned, im not going to use a ps2 to run it, im going to get the actually japanese gameboard from the arcade cabinet. I read/speak japanese so it shouldnt be a problem with translation, or ordering it. thats going to be the really hard part though, I have no idea how im going to get the guitars to work, as well as the drums.