Official Adapters
The Microsoft XBox 360 only supports official adapters because it cannot hold the drivers for the dozens of adapters available. As of 2010, Microsoft has released wireless 802.11g, b and n adapters for the 360. 802.11n is the latest and fastest standard. 802.11g gets real speeds around 22 megabits per second, while 802.11n achieves speeds of 100 to 140Mbit/sec, according to ComputerWorld. Also, 802.11n has twice the range of 802.11g.
Wireless Game Adapter
The only alternative to using the official wireless adapter is a wireless game adapter, according to electronics expert Jake Ludington. A wireless game adapter connects via the 360's Ethernet port, but has wireless capabilities to connect to your router. This option won't save much more than $10 off the price of an official adapter.
Tip
Consider using an Ethernet over power-line adapter, suggests Ludington. An Ethernet plug goes from the Xbox 360 to the Ethernet wall socket, and then from the socket to a wireless router. The advantages of this are that you can get much better speeds than with a regular Xbox adapter and you can pick up networks in your area.