We decided to book out flights with Singapore Airlines. We leave on 2nd September 2010 at 11:55. I also enquired about extra baggage allowance and received the following information from SIA.
Kindly note that if you hold unused/unstamped migrant visas that specifically state that you are permitted to remain in Australia indefinitely, then you will be entitled to double baggage allowance (40 kilos) on production of those visas at check-in. You can have as many items of luggage as you wish providing no one single item of baggage exceeds 32 kilos in weight. This is a health and safety requirement.
If you are not holding the correct visas at check-in, then you will be entitled to the standard free checked baggage allowance of 20 kilos per passenger.