Is timing more precise in Windows or Linux?

We are trying to start our program at one specific time, to the millisecond (For example, 12:00:00.000)..Using VB.NET on Windows we have found that (apparently, due to preemptive multithreading) there is always a very small few millisecond difference (For example, we actually start our thread at 12:00:00.012 sometimes or 12:00:00.006 at times, or somewhere in that range of just a handful of milliseconds)..My question is, does anyone know if our timing would be more precise if we were to do...

Is timing more precise in Windows or Linux?