Question : Xbox 360 and wired networking

I have many networked devices but this dang xbox makes me nuts, my first one gave me red ring.

So....
I purchased my sone a new one for christmas and wanted to checkout some of the other networking stuff, with tversity and online gaming.
PHYSICALY WIRED CONNECTION:
The first night it grabbed an IP with no issues, i was messing around with getting updates and stuff then figured out that i needed a subscritpion to do so....I moved on.
Played with windows media player and connected my pc only to find out that xbox does not support divix movies....I moved hooked up my laptop with the same cable and watched a movie.
The next evening i turned on the xbox and tried to play around, no ip, doh cable still plugged into my laptop. So i moved it from my laptop to my xbox and for the life of me cant get the xbox to grab an IP address. I even tried to give it a static IP. My suspision is that the xbox does not see that it is physicaly plugged in.

So to recap.
Xbox 360 purchased 8 days ago
First wired attempt at networking worked fine
Second wired attempt is a failure.
Linksys wireless router, but the xbox is physicaly wired to it.
All my other devices in the house work fine. 2 laptops wireless, 3 computers wired, and my iphone.

So i moved the cable and watched another movie :)

Answer : Xbox 360 and wired networking

May or may not matter, but just a thought. The cable that you are using, is it Cat-5 or Cat-6 and also Not a crossover cable? Just some other thoughts to throw in.