Like the sound of that, easy to use... Does Prestashop currently work in Australia and have Australia post module and one for eWay gateway?
I don't run an aus only site - so I stick to using paypal... easier for me. But you can use it for an aus site - and you do have eway and auspost modules available - but I think it's a paid module...
Joomla with Virtuemart is the best I have liked, and used. Also checked out Magneto, and didn't find many problems with it.
I've heard people having alot of luck with zen cart, although there arent many templates freely available.
First time e-commerce noob here I've been using Zen Cart for the customization aspect of it but Zen's quite temperamental everything I do seems to create a problem then It gets fixed and another one is created. If you don't know much PHP stay away unless you have plenty of time on your hands.
I would go with Zen Cart, Magento or Cubecart. Most of the time I use Wordpress with plugins for the small business ecommerce sites I build since the clients are sole proprietors just starting out and don't want to shell out the money for the time it would take to build and customize with one of the big-boy carts
A week ago started working on the prestashop store, very light, very fast, tons of default features. Poor seo, need to buy 150euro module or hire a programmer to tweak it. Template design is pretty easy to change if you just leave the default structure. So far very good experience with this shopping cart.