FYI, this person seems to have made a career ;-) of making sense of the Windows time functions:

http://stackoverflow.com/questions/7685762/windows-7-timing-functions-how-to-use-getsystemtimeadjustment-correctly

and their site:

http://www.windowstimestamp.com/description

Bottom line is that it's messy as everything else on Windows :-(  They claim, among other things:

- "GetSystemTimeAdjustment is not the function to look at."

- The undocumented NtQueryTimerResolution() is the function to look at.

- "Time Adjustment: 0.0156001 clearly identifies windows VISTA or higher with HPET and/or constant/invariant TSC on your system."

Screw it - I'm gonna go shovel more snow ;-)