Northbridge Disconnect - Question and or Confirmation

[Texun]

I have an XP2000 with WinXP Pro that runs in the 40's during normal use but when coming out of standby it reports temps in the mid 50's. Start using it and it cools down ASAP. It seems that I read something about WinXP manages the cpu cycles and will disconnect the NB when not in use. Is this true, and if so does this process of the OS stop when in standby? It's stable and nothing to worry about but I was just curious about what I *think* I read before about WinXP performing the same function as V-Cool or CPU Idle.

Thanks,