Hi it worked!
Thanks for the help!

Now, where do i configure the MAME controls?

I bought a Raspberry PI to do three things, Arcade, XBMC and a simple NAS.
XBMC and NAS+DLNA Server are working flawlessly. The arcade one still is a project under construction, but i am not giving up.
Attached you can see the setup now. My plan is to buy another Pi and put it inside the arcade controller, which is huge :)