conecting xbox 360 directly to modem problems

[grrrdoom]

i thought it would be easy to connect my 360 directly to my ambit 256 virgin media modem, just an ethernet cable between the two, but i can't get it to work.
i have tried a static ip address, power cycling etc but it still can't find an ip or use the static one.
i can connect my laptop and pc this way with no probs - am i missing something simple?
i really don't want to spend ��� on a wireless adaptor as the xbox is next to the modem at the moment!
any help please i have gone through all the steps on the xbox network connections screens with no joy.
cheers!

[Mattk]

if you are connecting via a modem dont you have to use a certain type of network cable?

net cables come as crossed or uncrossed. i cant remem,ber which is the standard but the other is the one that should be used.

this was the case when i 1st went online with the orig xbox may not be so now.