Setting up wireless with Homechoice

Can any one help me at all? I'm trying to set up a wireless connection
with our new Homechoice broadband. I have a wireless router - WAG354G -
which also has an inbuilt modem. With Homechoice I need to bypass this
modem, as the modem for our broadband is already built in. Problem is,
I've sorted the router out to send out signals but unfortunately I
still can't connect to the internet through the router. I'm at a loss
as to what to do. I'm reasonably IT savy, have followed the
instructions to a tea, and tried several alternatives. With still no
luck. I don't expect any one will have an exact solution, but has
anyone got any suggestions on where I can seek for help?! Please
please! Thanks.