Welcome to the discussions!
Can I use an AirPort Express if I have OS 10.4.11?
Yes. It would be a good idea to have
AirPort Utility 5.4.2 installed on your computer to configure the Express.
+iPhone picks up Wi-Fi in my living room, 80 feet away from the Comcast router, but my Macbook (2006) does not.+
Where does the MacBook pick up the signal?