Can I use any wireless adapter with the Xbox 360 or do I have to buy one that was made for Xbox 360?

There are two things you can use as an Xbox 360 wireless adaptor. The fist this is the actual wireless adaptor that is made for the Xbox 360. It cost me about $99. You can buy them at basically any game store. Your second option is using a laptop with wireless capabilities. All you need to do for this one is connect your computer to your Xbox 360 with an Ethernet cable. Then, right click on those two little computers that flash (the icon on your computer that shows when you are connected to the internet). Then when you click on that go to 'manage connections' and then you should get to a part where you see two connections (one is your Xbox, the other is your computer (which should be connected to the internet or this won't work). Also, make sure your Xbox is on too. So once you see those two connections, then highlight both of them (Ctrl+Click) on each connection and then click 'merge/bridge'. After you have successfully do this, you will be connected to the internet through your computer/laptop. I hope this was helpful.

Buy one specially made for the 360, they cost around £50. Or use an ethernet cable and plug it into the phone line. (Read the manual)

You have to use one made specially for the 360. you cant use one that you'd normally plug into a computer - I've tried.