Pro model. Keep an eye out because places like JB are intermittently doing good pack-in deals (your in Australia right?). The reason I say definitely pro is because you will want the DLC for GTAIV. Also, I wouldn't put it past MS to allow an HDD to be mandated for some games in the near future, so this model is a little more future proof (no console is remotely future-proof, but you know what I mean).
You CAN purchase and add an HDD later on, but it will cost more all up, and might be a hassle. Also, PLAY KAMEO. My god that was a fun little platformer, and can be found for $20-25 second hand. Bioshock as well.
Edit: By add and HDD I mean you can purchase an MS HDD (20gb or 120gb) and stick it on later. You cannot use a third party HDD.
starcraft - Playing Games = FUN, Talking about Games = SERIOUS
