Although I have a wireless router, buying a wireless network adapter for an Xbox 360 is an expensive $88 that I refuse to pay. For $12, I was able to purchase a Belkin 25' FastCat5E Ethernet Cable from Walmart.
I drilled two holes through my floor to my basement. Then I ran the ethernet cable from my living room where my Xbox 360 is located to my spare bedroom where my cable modem is located.
The Belkin FastCat5E ethernet cable connectors plug in and out easily whenever I need to move something around in my electronic equipment. The Belkin FastCat5E ethernet cable connectors are gold-plated, which offers a better data transfer rate without as much data loss. The gold connectors are important for a smooth Xbox 360 online gaming experience that doesn't have jerky screens and stalls. When selecting an ethernet cable for online gaming, make certain that you're buying the gold-plated connectors.
The Belkin 25' FastCat5E Ethernet Cable is a good value, and I've been very happy with it.