Changing my IP using existing netgear DG834 x 3...

Question

I intend to change my IP from Bigpond to Tadaust,because I recieve a pension and I will be able to use more internet for my money. Tadaust will not offer support for modems that arn't theirs. What settings in my computer do I need to change when they transfer my IP to Tadaust? Do I need to change settings in the modem and Outlook? I run windows XP. The modem is also connected to my wife's laptop which has Vista as the operating system.

Many thanks
John