Web Master:
We found one that fits that bill, its called Populus Balsam Spire.
It makes a very vigorous, large, narrow tree with white on the undersides of the leaves.
The leaf buds have a wonderful balsam fragrance in spring, which carries well on the breeze.
These trees are fast growing and therefore ideal for creating a quick screen.
Unfortunately we couldn't find a supplier in Australia - there are heaps in the UK, but none here (sorry).