By default, the top, right and left margins are set to 1 pixel. The bottom margin is set to 17 pixels since, initially, it contains the "Today" and "None" buttons. In the image below, all four of the calendar's margins are set to 10 pixels and are represented by the grayed section.
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2