You're half-right: Australia actually uses both. We use AV (known as "Preferential Voting" down here) for the House of Representatives, and PR for the Senate.
PR is perhaps more likely to produce a hung parliament, but it doesn't churn out "lots and lots of hung parliaments", as britboy claimed.
The 9 results where the party with the fewest votes got the majority of the seats was your Lower House so I guess your House of Representatives which uses the AV system.
And yes, more likely to produce hung parliaments but not a certainty
