Incorrect Time Sync Mac OS X reads hard…

Incorrect Time Sync

Mac OS X reads hardware date and time assuming it to be GMT, while Windows does not, and on a dual-boot system you will get a difference in time between the two systems equal to the difference in your local timezone and GMT/UTC.

The popular solution is to do something that makes either OSX or Windows change the hardware time each startup and shutdown, but if time zones don’t matter much to you, you can simply set your local time zone as GMT under Windows, and never adjust the date under Windows again. See this post on InsanelyMac for a more detailed discussion.