Bridging connections?

So I just my MacBook, and am loving it so far. However, I'm having a little trouble. I used my old Windows laptop as a metwork bridge for my Xbox 360. I had an ethernet cable connecting my laptop and Xbox, and bridged the wireless connection to the ethernet so that my Xbox could connect to the internet. I'm having trouble accomplishing the same thing on my MacBook.

I have the Xbox and MacBook connected via ethernet, and have enabled internet sharing from AirPort to ethernet in System Prefs. The Xbox passes the network test, but fails when trying to connect to the internet. However, at this point the MacBook still is connected to the internet and works fine, so something is blocking the Xbox from having access to the internet.

Everything worked fine with my Windows laptop, so I'm just wondering what to do. I'm new to Macs so I'm probably missing something very basic.

Thanks for any help you can give guys.
-Luke

 

Damn, I saw a reply to the thread and thought someone has solved it
But yea it's odd. It worked perfectly on my Windows laptop... and there's no way I'm going back to that thing