|If you have a wired connection from where you wish to put an additional wireless device to your existing router, I'd go with a wired solution.|
You could easily add another wireless capable SOHO router that has 4 LAN ports. This would give you more wired connections and extend the wireless. You could then configure the wireless on the second router exactly like on the first (same SSID and encryption key).
If you need info on how to do this, click on my name above in my reply and read my how-to guide on adding a second router to your LAN. You'll want to use the scenario wherein you interconnect the two routers LAN port to LAN port
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.