@moto
If you're in Oz, let me know. :-) Pints are never unwelcome.
The driving game rig will work with any PC or PS2 game that accepts steering wheel/pedal controls. The electronics is basically the same as an analogue joystic. IIRC the steering wheel has 270 degree rotation, which doesn't work very well in GT4. I have a mod in mind for this, which re-maps the voltage range of the steering wheel pot, to something more useful.
I don't currently have a machine to use with the rig though, and probably won't have for a while yet. I have vague plans for a media center PC, driving my projector, to use with both home theatre and gaming. I'm not sure how it is all going to pan out though, and it is not really a high priority for me.
edit- your MAME rig sounds like a damn good setup. MAME on demand is always a good thing. I also like the results from building with genuine arcade parts. The prices are very attractive, and the results are really good (professional?).