Open NAT for the XBox 360 Question?

[ly]

I am currently connecting my XBox 360 wired to my router.
I am wondering how I can Open NAT?
Do I configure it from my Laptop or the Desktop and I set my router up on?
And what does it actually do?Does it make my connection better?
Because I am always getting a 3 bar connection in Call of duty 4, maximum is 4 bars, wondering if open Nat will help?

Thanks so much!