The resolution of this property depends on the system timer.
Windows NT 3.5 and later
The Now property is frequently used to measure performance. However, because of its low resolution, it is not suitable for use as a benchmarking tool. A better alternative is to use the Stopwatch class.
You can also use the DateTimeOffset::Now property to retrieve the current local date and time. It allows a local time to be expressed unambiguously as a single point in time, which in turn makes that time value portable across computers.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2