If it is like my Samsung, 1080 refers to the standard native resolution of the TV. The pixel array is 1920X1080p using wobulation. So, any incoming signal will naturally get upconverted to 1080p.
That means the only issue is what is your incoming signal.
I assume you are connected via the HD component cables cables?
http://www.xbox.com/en-US/hardware/x...ponenthdcable/
1080i is the desired input (for me) from the 360. Your TV should not need any extra configuration to move the signal to 1080p. That should happen automatically.
W