This can help you :
I found a better solution to this
whole thing. The problem with the
Windows clock being off is because the
hardware clock (the one on your actual
motherboard) is being set to
"Universal" time, or GMT, when you
shut down your MacOS bootup. When you
boot Windows, Windows assumes your
clock is set to your local timezone
because that's what Windows does by
default. This explains why the people
who set their MacOS clock to GMT got
the right time in Windows... If the
hardware clock is being set to "GMT,"
when it's actually the local time,
Windows will pick this setting up as
local time as it did before.
To fix this, you need to add a key to
your Windows system registry to tell
Windows that your hardware clock will
always be GMT.
* WARNING: Editing your registry improperly can render your Windows
installation inoperable. Proceed VERY
carefully. I am not responsible if you
mess something up. *
The short solution for people who know
how to edit the registry: A DWORD key
needs to have the value of "1"
The step-by-step solution is as
1. Boot Windows
Click Start --> Run and type regedit. Click OK
The Windows Registry Editor should pop up. Navigate within the explorer
Click on the TimeZoneInformation "folder" from the navigation pane if
you haven't already done so.
This assumes the correct key doesn't exist. If it does, you will
just change the existing key's value:
Right click on the white space within
the folder (If you don't have a right
mouse button, you may need to download
a program called applemouse to emulate
the "control-click" of the apple
1-button mouse). Select new --> DWORD
Value. Title the key
"RealTimeIsUniversal" (No quotes). Set
the value to "1" (No quotes again).
Hexidecimal should be fine.
Either reboot and set the clock in MacOS or set the clock in Windows. You
should now be able to reboot into
either OS and have a correct clock.