I just installed Windows 7 on my MacBook and Windows STILL stores the local time in the hardware clock (as opposed to UTC) so when you reboot between the two OSes the time changes - dang! It turns out that there's a secret registry key that gets Windows to behave 'normally' in this respect. You just need to add a new DWORD key, called RealTimeIsUniversal (which should be set to 1), at the following place in the registry (and then reboot to make it take effect):
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation
Here's all the details from a man who knows....
