Did you bridge the connections? Did you make a static route to route traffic between the two interfaces?

http://www.tldp.org/HOWTO/text/Bridge+Firewall
http://www.tldp.org/HOWTO/text/Bridge

These documents might help.

Thanks I will look further into this.
Sorry if this sounds silly but in order for me to access the net from the linux box (with the external IP) going through the ADSL modem, does the bridging even matter? What I mean is, gateway aside, if I only had the linux box with the extermal IP (for example, if the Linux box was the web server) and the DLINK modem, then the bridging should not be necessary should it? It is actually the linux box that cant access the internet so there is no hope for anything behind it to be able to access either whether bridging is set up correctly or not I would think.
Sorry if I am incorrect in my assumption.

Here is the layout of my network in case this helps. Does anyone think it will help if I put the Asante router between the Dlink and Linux box? Would I still be able to have an external IP? Unfortunately I am not at home right now so I can't post the config yet.

Telus
||
------------------------
|DLink 3001 modem|
------------------------
||
----------------
|EXT IP (180...|
----------------
| Linux |
----------------
|INT IP (10... |
----------------
||
---------------------
|Ext IP (180... | WAN Port
---------------------
|AsanteFR3004LC|
---------------------
|Int IP (10..1 | LAN Ports
---------------------
||
----------------
|Int IP (10.. |
----------------
|Windows box |
----------------

http://yolinux.com/TUTORIALS/LinuxTu...rkGateway.html

This link explains how to set up a NAT or gateway with linux machine. I've set this in my office and its working fine .