I have adsl with internode at the moment.
The change to adsl on the connection you want - i have the same - is definately worth it. Dial up sucks.
These guys here are also really good apparently.
I can't confidently answer how it'd be for online gaming. I'd think you'd prob want to go a higher speed(or have a really good pc) and make sure you found a local server to play on otherwise it may not be that good.
I might try on quake 3 with my connection at home and see how it goes.
As far as overall speed is concerned its def worth it. I'm in the same boat and can't get cable here either but ADSL sure as hell makes up for it.
Proud TQE Operator
1999 Black Manual AU XR6HP
Unichip equipped by Autotech Engineering, Granville
Cam install by Crescent Motorsport, Liverpool