Connecting an original Xbox to computer...

...and using the computer's wireless connection to my router. Over the weekend, I moved my router (Linksys WRT54G), Cable Modem (Motorola Surfboard), and Xbox 360 down to my basement. By using a wireless adapter on my computer upstairs, I am able to connect to my router in the basement almost flawlessly. However, here is the somewhat annoying problem: I now don't have any way to connect my original Xbox (softmodded with XBMC) to the router, and a long Cat5 cable is out of the question. Is there anyway to use the one free ethernet port on my computer to pass through my Xbox connection to the router via my computer's wireless connection? I looked around online, but I haven't found the best way to phrase it, as I am getting minimal results, much of which are more about the 360 than the Xbox. I attached my artful representation of said situation. Hopefully it helps.

tl;dr

1. Moved router downstairs, computer now connected through wireless adapter.
2. Original Xbox used to be connected through said router, now nothing.
3. Want to connect Xbox through PC with CAT5 to use wireless connection.
4. ???
5. Profit!

Case closed.

I figured out how to connect it. Instead of using Internet Connection Sharing through my wireless adapter, I had to create a bridge from my wired connection (Xbox to PC) to the wireless connection. I now flawlessly can stream my media proper, and my RSS feed works as well on XBMC.