Thanks everybody for the replies and to CraigB for raising the subject. Ashore's debit card solution is great and will solve my objections on that score as well as providing security for internet purchases.
I chose Telstra ADSL because my mobile and home phone are with them, so I get a small rebate. Also they had a self-install kit so I didn't have to lose a day's income waiting at home for a technician. (the house has Optus cable but Optus wanted to go through the whole install process again - permission from landlord, inspect the premises, blah, blah.)
I still have a few months to run on the Telstra contract but after that will definitely look at all the options put forward.
regards
Coldamus