Definitely go for cable if you are in Australia! ADSL only really necessary in Countries like US as there are way too many cable users, in result, slow speed connection.
There are still not enough cable users in Australia compare to other countries to really max out the cable bandwidth. A technician from Telstra told me that. Maybe in the future like 5 years later, then we might have to consider using ADSL, when there are too many cable users.
Cable is cheaper, and way faster than ADSL atm.