Sleep(milliseconds)

I'd call timeBeginPeriod(1) in your emulator's intialization code, and timeEndPeriod(1) in the deinitialization code. It should make time slices 1ms in length(average best case).

For timing when sound is disabled, I use QueryPerformanceFrequency() and QueryPerformanceCounter(). If a "performance counter" is not available(read the docs on those two functions), I fall back on GetTickCount().