the process name of fences

I think it may load as part of explorer.exe

Hi gm3000, yes Neil is correct Fences loads as part of explorer. If you'd like to observe a 'rough' figure you may start by killing explorer, renaming the DesktopDock.dll module (or DesktopDock64 on 64bit) of Fences, starting explorer/measuring...then repeating and putting it back.

woow,thats so cool! so , do you know how much memory  fences occupied?

Try it yourself, I just did. The difference with Fences running is just 3MB  

(If you're running on XP, you'll experience a few MB more ; on XP it has to load the background image in to memory also)