Why only one?While most any other USB network adapter would "technically" work, the Xbox doesn't have the software to support it. Thus Microsoft forces you to purchase their wifi card
However, it would be possible to get something like an access point or router and configure it as a "wireless card" of sorts...
http://www.cellfanatic.com/2008/01/13/router-dd-wrt-low-cost-xbox-360-wireless
I might try this sometime with my router... I have one with DD-WRT but never tried connecting to another wireless network.
While most any other USB network adapter would "technically" work, the Xbox doesn't have the software to support it. Thus Microsoft forces you to purchase their wifi card
However, it would be possible to get something like an access point or router and configure it as a "wireless card" of sorts...
http://www.cellfanatic.com/2008/01/13/router-dd-wrt-low-cost-xbox-360-wireless
I might try this sometime with my router... I have one with DD-WRT but never tried connecting to another wireless network.