Hi there I was just wondering if it's possible to use a Cisco wireless adapter on an Xbox 360
Is it a USB adapter? If so, it won't work unless it specifically states that it's made for XBox 360.
Standard USB wifi adapters require drivers, which can't be installed on the 360. There are only a few USB adapters available that will work, including the one from Microsoft.
You can use a standard wireless bridge which will plug in to the Ethernet port on the XBox.