Setting up Linksys WRT54GL with ADSL Modem

[#1]

Hey,
I posted a while ago about trying to setup a Linksys WRT54GL but never got round to managing it. Now I've decided to try again so hopefully someone will be able to advise me.
This is how I hope my network will look like:
                                                Internet
                                                    ||
                                    TP-Link TD-8840 (Modem)
                                                    ||
                              Linksys WRT54GL (Main Router)
                                  //                ||                \\
                        Computer 1      Computer 2      Laptop
I've setup the 8840 Modem in bridged mode with the VCI and VPI as 0-38. The WRT54GL is setup as PPPOE and I have logged in but it is still not connecting to the internet. I noticed that "Service Name" is not filled in though, is there something I have to put there? I put the Wireless Mode as Access Point, is that correct?
Hopefully someone can point me in the right direction, didn't realise it would be this much a nuisance to setup!
Thanks.

[#2]

To me it's not clear how the TP-Link handle bridge mode. If you just want the WiFi from the WRT54 I would suggest to run the TP-Link normally and connect the WRT54 internet port to one of the ethernet ports of the TP-Link.
You may have to setup the WRT54 before connecting to the TP-Link and you need to select DHCP on the internet side and diasble DHCP  on the LAN side of the WRT54.