The idea is awesome. How much of the logistics do you have worked out? Like, do you have a world map? Do you have a rough idea of how long the game will be? Do you know any specific areas that will be covered? Do you know who the main villain is? Is there another villain? Or even some kind of oligarchy type structure?
I've tried making games before myself. None lasting more than a month or two in time I've worked on it, and none of them have come close to being finished. I don't know RMXP that well, but I can do music fairly well, and I can of course do testing. (then again... who can't?)
I'm also good with storylines (or so I've lead myself to believe) Just ask me what you need, and I'll get it done.
I have samples of the music I've done. I'll edit this post later when I have a link.
edit: http://winegarden.homeip.net/phoenix...hp/Music_stuff
Also, there's a wave file I made on that page too. And keep in mind, this is just a small selection. I have more, and can make whatever you want.