hi-res counter

So I'm coding a game and trying to maintain a steady game speed (ie. framerate) and I found some Windows functions called QueryPerformanceCounter and QueryPerformanceFrequency.

Using these looks more reliable for controlling a game loop than say, clock() shit from time.h or something.  The only problem is that I've seen this:

>If the installed hardware supports a high-resolution performance counter

I've tried it and it works 100% fine on my machine.  But I'm wondering what sort of hardware would NOT support this?  Is it likely that if I distributed my game that many users would not have the performance counter?

>>1

QueryPerformanceFrequency and Counter do not work on multiprocessor machines unless you do something like call

SetProcessAffinityMask(GetCurrentProcess(), 1L);

But I dunno because I only have 1 processor.