Thanks uman. Yes, I came across GroovyMame but there was the extra inconvenience of sourcing a graphics card with 15Khz output and having to knock up a suitable PC with drivers etc. In the end, RPI works fantastic. Even games such as Dangeron Feveron (one of the best shooters ever IMHO) plays at 60fps rock solid. The RPI takes up little space and is currently connected to my 360 controller. I do intend to build a cab around the RPI (compact, of course!) with a *proper* controller when I have time. But, for now, it's the nearest thing to being in an arcade running actual PCB's
God, I miss those dark, musty arcades ....