I have a DGL-4100 behind a Linksys DSL rou...

Hi,
It is very easy to set up your router.
You dont need the disc.
First make sure that you are able to go online when connected directly to the modem.
Click Here for Step by step Guide

zSB(3,3) Installing a Two Router Network Installing a router to work as the second one on a home network requires special configuration. Do the following on the second router to ensure it (and the devices attached) function properly:

1. Connect as local device or bridge - If connecting the second router via Ethernet cable, plug it into one of the LAN ports on the first router. If connecting the second router wirelessly, ensure the second router is set for client mode. Note that some home wireless routers do not support client mode; these must be connected by cable. Check your router documentation for details on its client mode configuration support.

2. Check / change IP address - Most home network routers use a default IP address setting. Often, these default IP addresses will not work in a two router environment. Check the second router's IP address value and reset it if necessary to work within the valid address range of the first router (and to not conflict with any other device on the network).

3. Disable DHCP - To avoid IP address conflicts between all of the devices on the home network, only one of your two routers should assign addresses via DHCP. All mainstream routers provide an option to disable DHCP as part of the router's configuration screens.

Instead of adding a second wired router to an existing network, consider adding a network switch instead. A switch accomplishes the same goal of extending the size of a network, but it does not require any IP address or DHCP configuration, greatly simplifying configuration.