I have a Comcast cable

Question

I have a Comcast cable modem (Arriss) with a Linksys router attached to a Dell PC desktop in one room. In an other room is a Dell PC laptop with a Linksys Wireless -G Notebook adapter card inserted. I am able to access the internet (AOL) with the desktop but I couldn't access the internet with the Laptop. Both are running XP. After speaking with comcast, I am now able to access the internet with the laptop but it is not secured. How can I secure the AOL connection?