Virgin Blue is on the up, last I'd heard they were looking for 400 pilots over the next 12 months, all in the 738. As expat said you'll need a visa to work there and they don't come easy. In fact they're as difficult to get as it is to get a Green Card.
As far as the conversion is concerned, the Australians are a bit more realistic than the Brits. If you have an FAA ATP, you'll need to take 3 exams. Air Law, Human Perf and the Instrument exam. Then you'll need to take whats called the "Command Instrument" Flight Test, which can be included on your CPL flight test. There's no ATP flight test.
If you can get the right to work and live there, you can get into a Boeing with less than 2000 hours.
Take it easy.