Hi:
May be this is not what you looking for but here is an idea for your consideration.
If you have a wireless router, consider hooking up your Xbox directly to it, this will save you some headache and trouble.
In my case I set up my network like this:
Wire: modem=router=XBOX 360
Wireless: 2 PC's and a laptop
(I bought 2 AZIO usb wireless adapters for my PC's for $14 each on newegg cheaper than buying the $100 Xbox wireless adapter!)
Since my Xbox was going to be in my home theater all the time I just change my modem and router location to my living room, I also setup my network for sharing all media between devices, so I can stream movies, music and pictures from my computer to my XBOX. But may be this is not your case!
Now; to your question, I know that you already know that you could use your wireless laptop as and wireless adapter for your XBOX, you should try checking out this post:
http://www.computerhope.com/forum/index.php/topic,69901.0.htmlThere's also some tutorial on you tube about this matter.
But keep in mind that if you do so maybe you will have to keep your laptop close to your XBOX all the time!