Wireless network config problems

Hey,

I need help trying to re-configure a network connection.

Equipment/ Set-up:
I have a Linksys broadband modem with 4-port switch (model WRT54G v5) and a ZyXEL wireless router Prestige 600 series (model no. 401380) with a Dynalink ADSL connected to the phone jack. We recently changed the name of the account over from my house mate and had difficulty with the phone line and thus the network connection.

We have a laptop on Windows XP and a Mac OS laptop. The modem and router are connected to each other and a network cable from the broadband modem connects to the laptop (Windows XP).

Problem:
The connection is back on and is strong but I am unable to connect to the wirless network. The LAN network has been reconfigured without any hassles. It is configured to PPPoE. A mate has said that the correct option for us in our network grid is PPPoA but that option doesn't come up on the linksys site.

I initially had the option to connect to a couple of networks including a linksys network but it was unsecured. I am trying to access the wireless network my housemate previously configured for our place but it has a red cross through it.

Hope this is the right info to get some suggestions on:
1. how to reconfigure to the wireless network (and to the specific one we want)
2. how to get on to PPPoA if this is the correct selection for us.

Cheers