you dont want to replace it..

you can get wireless internet.

Just plug your RJ45 to one of the four RJ45 LAN Ports in the Wireless ADSL gateway and you will be able to receive wireless in the name Linksys.

You can send me the model no i could help you in better way.

if you are wishing to give wireless a desired name and security protection. you should do the following.

get one more patch cable ( i mean RJ45 Cable)

Connect one end to the Adsl gateway ( any of the four LAN (RJ45) ports)

The other end to your pc or laptop network port.

take interent explorer and type 192.168.1.1

it will ask for user name & password.

Give username: admin

Password : admin

you can see Linksys Setup page.

on top select wireless ..

in that page you can see Wireless SSID : linksys

change it what you want to give your Wireless Name. and click save ( dont forget to save)

Second you can see wireless security

Select any of the encryption and set your password.

Click Save and Done

Remove the cable from your laptop and try to connect through wireless.

On the gateway you can see the wireless light will be blinking.

Now you can get wirless internet.. the router( gateway) is working as switch+Accesspoint.