Getting Online

A couple of days ago a friend came over and brought a wireless network adapter so we could play online. As it was the first time I went online I was entitled to 1 month free trial of Xbox live gold which I started. Then wen he left he took his adapter which means I can't get online but I'm slowly using up my free trial. I am thinking of buying a wireless network adapter but the cheapest one I've found is £44.99. Over the past days I have been trying to turn on ICS on my laptop so that if I plug the Ethernet cable from the Xbox to the laptop the laptop will pick up the wireless signal and send the internet to the xbox. For some reason when I try to click properties of the LAN which is where the setting to turn ICS on is it says "an unexpected error has occurred". I searched on the Microsoft website and it says it's because of a corrupted registry and gave instructions on how to fix that. When you replace the registry you can access the properties of the LAN and turn on the ICS.
So now you might be wondering why I'd want to buy a network adapter for my xbox if I can turn on ICS. Well it turns out that with replacing the corrupted registry a side effect is that your internet is disabled. I have tried using the internet wirelessly and plugging it into the router but it refuses to connect to the internet. In the end I had to do a system restore to get the internet back but that means that the registry is re-corrupted.
I'm not sure if I should go through the hassle of trying to get it to work or just to buy a wireless network adapter.