Mathew, sorry to join this so late, I set up exactly the same config 2 weeks ago, I bet you're from SA?
What you need to do is setup you username and password on the ADSL router, which you must have done if you've tested it from another machine.
Then on you e-smith you set it as a dedicated connection with a STATIC ip address, NOT PPOE, yes you need 2 network cards, the static IP (If I'm correct in assuming your from SA) of the second NIC should be 192.168.10.100.
The reason It isn't working the way you set it up, is because your machines are looking to the sme box for proxying, if you want to plug the router directly to the switch (not recommended), you would point your machines to the IP address of the router (assuming again) 192.168.10.200.
Let me know if you need any more help
Steven