each x-box has its own x-box live account. Connecting using ethernet cables through a router. at the moment when a x-box is on x-box live when the other comes on the first one gets disconnected. we need them to be both on at the same time.
What probably is going on is a IP conflict.
First go to your Pc hit start then run type in cmd
in the black box that comes up type in ipconfig
write this info, mainly
Default gateway..........192.168.X.X
do not put the same IP adress as the pc or this will kick you off live when the pc connects to the internet
Try this on both xbox's but put a diffrent last numbers like 192.168.1.XXX and 192.168.1.YYY
When you set the xbox's settings use the same default gateway as the pc.
http://www.portforward.com/networking/staticip-xbox360.htm
Try this on both xbox's but put a diffrent last numbers like 192.168.1.XXX and 192.168.1.YYY
they have the old dashboard pics but if you hit the guide button ( the big one) it should be similar enough to get you along.
If you run into any problems let me know
Good luck!