You can add the Wireless Access Point or WAP. Widely available and plenty to read on many web sites.
I have a Broadband router and a hub, both linksys. I'm moving into a two floor apartment. I am going ot have a desktop on the second floor with the router. On the first floor I will have both an ethernet media center device and a laptop (has 802.11g and 1gigabit). I would like to avoid wiring between floors. What is the best solution