How to get changed Computer Name without restarting the computer

Hi,
 
I changed a computer from "A" to "B" . I don't restart the computer. When I use System.Environment.MachineName I get "A" and not "B" - which correct. But when I see " System Property page" , " Computer Name tab " I see computer name as "B".

Where does "B" get saved in Windows memory and how do I access that value.

Please can somebody help me on this.