We got back from Oz OK and can share some of our experiences re cash machines.
The Thomson pre loaded card was super.There was a standard transaction fee of AUD3, but no card charges if we used Commercial bank ATM's (yellow and black sign). There were text updates every time we used it at an ATM, but we could also set up an internet account and check balance whilst blagging free wifi from Starbucks (well if they won't pay UK tax...).
BEWARE!! HSBC charge an additional AUD2 per transaction and we got charged for a credit card transaction at Ayers Rock when we hit the wrong button at the ANZ machine.
Once we found Commercial Bank, we didn't experiment with any other machines, and we found that the three dollar charge wasn't part of the overall transaction. So, if you asked for $300, that's what you got, but the text update from Thomson put the total transaction at $303.
The card can also be used like a debit card for paying for meals, etc or buying gifts.
It was so easy to get the money back off Thomson when we returned, so we will probably use the Euro card when we venture abroad this year and hit the hole in the wall instead of taking travellers cheques.