beginners set up info -

[#1]

OK, here's what I've got - 2 PC's (both Vista) one hard wired to BT 2wire router the other upstairs via wireless. X-box trying to get online via it's cable to the PC upstairs.
Got as far as watching movie trailers on X-box but I think that was via Windows Media Centre?
After playing with all sorts of settings we got past the first few but never successfully to the end.
Is there a simple list of what we need somewhere to get on X-box live?
Keep it simple please, not good at wireless and know nothing about kids X-box

[#2]

i think this is what u r trying to do. cable from xbox to pc's upstaris and use its wireless.
try this if so.
1. go to network and sharing centre, then manage network connections. u should see the wireless adpater and your ethenet adapter(local area)
2. theres two ways to do this the first is easy but most likely you will get mod/strict nat on xbox test.
its called internet connection sharing(ICS) look at the capture below. To get the ics box up right click the wireless adapter and choice propites. And tick the share this connection option and save. you may need to reboot the pc
thats it should be up and running now.
If your kids find they cant speak to the odd friend/connect to certain game rooms. then do a network test on the xbox if the nat test comes back as strict or mod then you will need to try the bridged method or better run a cable to the router(cable is allways best for gaming)
let us know how you get on